СТРУКТУРНАЯ ОРГАНИЗАЦИЯ, ФУНКЦИЯ И

Реклама
2006
ÖÈÒÎËÎÃÈß
Ò î ì 48, ¹ 11
ÑÒÐÓÊÒÓÐÍÀß ÎÐÃÀÍÈÇÀÖÈß, ÔÓÍÊÖÈß
È ÄÈÍÀÌÈÊÀ ßÄÅÐÍÛÕ ÏÎÐ
© Í. Â. Ãóáàíîâà,1 Ê. Í. Ìîðîçîâà, Å. Â. Êèñåëåâà 2
Í. Â. Ãóáàíîâà, Ê. Í. Ìîðîçîâà, Å. Â. Êèñåëåâà
Ñòðóêòóðíàÿ îðãàíèçàöèÿ, ôóíêöèÿ è äèíàìèêà ÿäåðíûõ ïîð
Èíñòèòóò öèòîëîãèè è ãåíåòèêè ÑÎ ÐÀÍ, Íîâîñèáèðñê;
ýëåêòðîííûé àäðåñ: 1 [email protected]; 2 [email protected]
 îáçîðå ñóììèðîâàíû ïîñëåäíèå äàííûå ìîðôîëîãè÷åñêîãî è áèîõèìè÷åñêîãî àíàëèçà ÿäåðíûõ
ïîð — ñëîæíûõ ñòðóêòóðíûõ êîìïëåêñîâ, ÷åðåç êîòîðûå îñóùåñòâëÿåòñÿ ïàññèâíûé è àêòèâíûé ÿäåðíî-öèòîïëàçìàòè÷åñêèé òðàíñïîðò â ýóêàðèîòè÷åñêîé êëåòêå. Ðàññìîòðåíû îñîáåííîñòè ñòðîåíèÿ ÿäåðíûõ ïîð ó íèçøèõ è âûñøèõ ýóêàðèîò, ìîëåêóëÿðíûå àñïåêòû ïðîöåññîâ èìïîðòà ìîëåêóë â ÿäðî è èõ
ýêñïîðòà â öèòîïëàçìó, à òàêæå ôàêòîðû, ó÷àñòâóþùèå â ðåãóëÿöèè ýòîãî ïðîöåññà. Îñîáîå âíèìàíèå â
îáçîðå óäåëåíî âîïðîñó ôîðìèðîâàíèÿ ÿäåðíûõ ïîðîâûõ êîìïëåêñîâ in vitro è in vivo â ìèòîçå.
Ê ë þ ÷ å â û å ñ ë î â à: ÿäåðíûå ïîðû, ÿäåðíî-öèòîïëàçìàòè÷åñêèé òðàíñïîðò, äèíàìèêà ÿäåðíûõ ïîð,
ìèòîç.
Ï ð è í ÿ ò û å ñ î ê ð à ù å í è ÿ: ßÏÊ — ÿäåðíûé ïîðîâûé êîìïëåêñ, ÝÏÐ — ýíäîïëàçìàòè÷åñêèé ðåòèêóëóì, ÃÒÔ — ãóàíîçèíòðèôîñôàò.
Óëüòðàñòðóêòóðíàÿ îðãàíèçàöèÿ ÿäåðíûõ ïîð
Ïîÿâëåíèå ÿäåðíîé îáîëî÷êè â êëåòêàõ ýóêàðèîò
îáåñïå÷èëî ðàçäåëåíèå ïðîöåññîâ ðåïëèêàöèè è òðàíñêðèïöèè ÄÍÊ, ïðîèñõîäÿùèõ â ÿäðå, îò ïðîöåññîâ ñèíòåçà áåëêîâ â öèòîïëàçìå, ÷òî îáåñïå÷èëî áîëåå òî÷íûå
ìåõàíèçìû ðåãóëÿöèè ýêñïðåññèè ãåíîâ. Îñîáóþ ðîëü â
ïðîöåññå âçàèìîäåéñòâèÿ ÿäðà è öèòîïëàçìû èãðàþò
ÿäåðíûå ïîðîâûå êîìïëåêñû (ßÏÊ), êîòîðûå âõîäÿò â
ñîñòàâ ÿäåðíîé îáîëî÷êè. Èíòåðåñ ê óñòðîéñòâó è ìåõàíèçìàì ôóíêöèîíèðîâàíèÿ ßÏÊ íå ñíèæàåòñÿ, íåñìîòðÿ
íà áîëüøîå êîëè÷åñòâî èññëåäîâàíèé è ðàáîò, ïîñâÿùåííûõ ýòîé òåìå. Áëàãîäàðÿ äèíàìè÷åñêèì èçìåíåíèÿì â
ðàçëè÷íûõ êîìïàðòìåíòàõ ßÏÊ îáåñïå÷èâàþò êàê ïàññèâíûé, òàê è àêòèâíûé ïåðåíîñ ìåëêèõ è êðóïíûõ ìîëåêóë, ðàçìåð êîòîðûõ çíà÷èòåëüíî ïðåâûøàåò äèàìåòð êàíàëà, ÷åðåç êîòîðûé îñóùåñòâëÿëñÿ òðàíñïîðò.  ñâÿçè ñ
ýòèì èñêëþ÷èòåëüíîå çíà÷åíèå èìååò èññëåäîâàíèå óëüòðàñòðóêòóðíîãî ñòðîåíèÿ ßÏÊ êàê â íåàêòèâíîì ñîñòîÿíèè, òàê è íà ðàçíûõ ýòàïàõ òðàíñïîðòà ìîëåêóë. Íå ìåíåå èíòåðåñíûì ÿâëÿåòñÿ âîïðîñ î ñåëåêöèè òðàíñïîðòèðóåìûõ ìîëåêóë. Áëàãîäàðÿ ìîëåêóëÿðíî-áèîëîãè÷åñêèì
èññëåäîâàíèÿì ê íàñòîÿùåìó âðåìåíè óäàëîñü âûÿâèòü
îñîáûå ïîñëåäîâàòåëüíîñòè â áåëêàõ ßÏÊ, êîòîðûå
âçàèìîäåéñòâóþò ñ òðàíñïîðòíûìè ôàêòîðàìè è îïðåäåëÿþò íàïðàâëåíèå ïåðåìåùåíèÿ òðàíñïîðòèðóåìûõ ìîëåêóë â ÿäðî èëè â öèòîïëàçìó. ßâëÿÿñü ñëîæíîîðãàíèçîâàííîé ñòðóêòóðîé, ÿäåðíûå ïîðû òåì íå ìåíåå ñïîñîáíû áûñòðî ñîáèðàòüñÿ è ðàçáèðàòüñÿ, ÷òî ïðåäïîëàãàåò
íàëè÷èå îñîáûõ ìåõàíèçìîâ ðåãóëÿöèè ýòèõ ïðîöåññîâ,
êîòîðûå áûëè èçó÷åíû áëàãîäàðÿ èñïîëüçîâàíèþ êîìáèíàöèè ðàçëè÷íûõ ìåòîäîâ.
Öåëüþ íàñòîÿùåãî îáçîðà ÿâëÿåòñÿ îñâåùåíèå îñíîâíûõ ðåçóëüòàòîâ, ïîëó÷åííûõ ê íàñòîÿùåìó âðåìåíè ïî
âûøåïåðå÷èñëåííûì âîïðîñàì, à òàêæå îáñóæäåíèå ðàçëè÷íûõ òî÷åê çðåíèÿ, êàñàþùèõñÿ ñòðîåíèÿ, ôóíêöèîíèðîâàíèÿ è ôîðìèðîâàíèÿ ßÏÊ.
ßäåðíî-öèòîïëàçìàòè÷åñêàÿ àêòèâíîñòü êëåòîê îáåñïå÷èâàåòñÿ âî ìíîãîì òðàíñïîðòîì ðàçëè÷íûõ ðåãóëÿòîðíûõ ôàêòîðîâ, áåëêîâ è ÐÍÊ ÷åðåç ßÏÊ, ïîýòîìó èññëåäîâàíèþ ìîðôîëîãèè ýòîé îðãàíåëëû óäåëÿåòñÿ áîëüøîå âíèìàíèå. ßäåðíàÿ ïîðà ïðåäñòàâëÿåò ñîáîé ñëîæíîå
íàäìîëåêóëÿðíîå îáðàçîâàíèå äèàìåòðîì îêîëî 120 íì
è ìîë. ìàññîé îêîëî 125 ìÄà, ôîðìèðóþùåå 30-íàíîìåòðîâûé êàíàë â ÿäåðíîé îáîëî÷êå (Akey, Radermacher,
1993). ßÏÊ ïðîÿâëÿåò âîñüìèêðàòíóþ ñèììåòðèþ è ñîñòîèò èç íàáîðà 30 ðàçíûõ áåëêîâ — íóêëåîïîðèíîâ
(Vasu, Forbes, 2001; Cronshaw et al., 2002). Âñåãî ÿäåðíàÿ
ïîðà ñîäåðæèò îêîëî 1000 áåëêîâ è âêëþ÷àåò â ñåáÿ òðè
îñíîâíûõ êîìïàðòìåíòà: öåíòðàëüíûé è äâà àñèììåòðè÷íûõ ïåðèôåðè÷åñêèõ — öèòîïëàçìàòè÷åñêèé è âíóòðèÿäåðíûé (Hinshaw et al., 1992; Ris, 1997).
Öèòîïëàçìàòè÷åñêèé êîìïàðòìåíò íàõîäèòñÿ íàä è
íåïîñðåäñòâåííî â ïëîñêîñòè íàðóæíîé ÿäåðíîé ìåìáðàíû è ñîñòîèò èç òîíêîãî è çâåçä÷àòîãî ãîðèçîíòàëüíûõ
êîëåö (ðèñ. 1, à, á, ä). Òîíêîå êîëüöî èìååò òîëùèíó îêîëî 20 íì è íåñåò âîñåìü ñóáúåäèíèö ðàçìåðîì îêîëî
30 íì, ê êàæäîé èç êîòîðûõ ïðèêðåïëåíà íàïðàâëåííàÿ â
öèòîïëàçìó êîðîòêàÿ öèòîïëàçìàòè÷åñêàÿ ôèáðèëëà.
Öèòîïëàçìàòè÷åñêèå ñóáúåäèíèöû ñèäÿò íà òîíêîì êîëüöå, êàê áóñû íà íèòêå, è ìîãóò âðàùàòüñÿ, ïðèáëèæàÿ
ëèáî óäàðÿÿ ôèáðèëëû îò âõîäà â êàíàë ïîðû (Goldberg,
Allen, 1996; Kiseleva et al., 1998, 2000). Çâåçä÷àòîå êîëüöî íàõîäèòñÿ ïîä òîíêèì êîëüöîì, òåñíî ñâÿçàíî ñ íàðóæíîé ìåìáðàíîé ÿäðà è ñîäåðæèò âîñåìü òðåõãðàííûõ
âûðîñòîâ, ðàñïîëàãàþùèõñÿ ìåæäó öèòîïëàçìàòè÷åñêèìè ñóáúåäèíèöàìè. Ïðèíàäëåæíîñòü ê öèòîïëàçìàòè÷åñêîìó êîìïàðòìåíòó åùå îäíîé ñòðóêòóðû — ïåðèôåðè÷åñêîé ãëîáóëû, çàêðûâàþùåé âõîä â öåíòðàëüíûé êàíàë ñî ñòîðîíû öèòîïëàçìû (íà ðèñ. 1, ä íå ïîêàçàíà), —
887
888
Í. Â. Ãóáàíîâà, Ê. Í. Ìîðîçîâà, Å. Â. Êèñåëåâà
Ðèñ. 1. Ìîðôîëîãèÿ ÿäåðíûõ ïîðîâûõ êîìïëåêñîâ è ñõåìà ñòðóêòóðíîé îðãàíèçàöèè èíäèâèäóàëüíûõ êîìïîíåíòîâ ÿäåðíîé ïîðû
(ìîäèôèöèðîâàíà èç: Allen et al., 2000).
à — âèä öèòîïëàçìàòè÷åñêîãî êîìïàðòìåíòà ÿäåðíûõ ïîð îîöèòîâ Xenopus â ïðîñâå÷èâàþùåì ýëåêòðîííîì ìèêðîñêîïå; á — âèä öèòîïëàçìàòè÷åñêîãî êîìïàðòìåíòà ÿäåðíîé ïîðû òîãî æå îáúåêòà â ñêàíèðóþùåì ýëåêòðîííîì ìèêðîñêîïå; â — ïîïåðå÷íûé ñðåç ÷åðåç ÿäåðíóþ îáîëî÷êó, äåìîíñòðèðóþùèé áàñêåò-ñòðóêòóðû ÿäåðíûõ ïîð (îòìå÷åíû ñòðåëêàìè) îîöèòîâ Xenopus â ïðîñâå÷èâàþùåì ýëåêòðîííîì ìèêðîñêîïå; ã — áàñêåò-ñòðóêòóðû
ÿäåðíûõ ïîð òîãî æå îáúåêòà â ñêàíèðóþùåì ýëåêòðîííîì ìèêðîñêîïå; ä — ñõåìà îðãàíèçàöèè ÿäåðíîé ïîðû è ôîòîãðàôèè åå èíäèâèäóàëüíûõ êîìïîíåíòîâ, ïîëó÷åííûå ñ èñïîëüçîâàíèåì ñêàíèðóþùåãî ýëåêòðîííîãî ìèêðîñêîïà.
äî ñèõ ïîð îáñóæäàåòñÿ.  íàøèõ èññëåäîâàíèÿõ (Kiseleva et al., 1998), ïîñâÿùåííûõ èçó÷åíèþ äèíàìèêè ÿäåðíûõ ïîð â ïðîöåññå ýêñïîðòà ÐÍÊ â êëåòêàõ ñëþííûõ
æåëåç õèðîíîìóñà, áûëî ïîêàçàíî, ÷òî ïåðèôåðè÷åñêàÿ
ãëîáóëà îñòàåòñÿ ñâÿçàííîé ñ ßÏÊ â ïðîöåññå òðàíñïîðòà ìîëåêóë.
Öåíòðàëüíûé êîìïàðòìåíò ÿâëÿåòñÿ íàèáîëåå ìàññèâíîé ÷àñòüþ ßÏÊ, ôîðìèðóåò öåíòðàëüíûé êàíàë
ïîðû è ñîñòîèò èç äâóõ ñèììåòðè÷íûõ ÷àñòåé (ðèñ. 1, ä).
Êàæäàÿ èç íèõ âêëþ÷àåò â ñåáÿ ôðàãìåíò öèëèíäðè÷åñêîãî òðàíñïîðòåðà è äâà êîëüöà — âíóòðåííåå è òðàíñìåìáðàííîå, êîòîðîå ïðîíèçûâàåò ÿäåðíóþ ìåìáðàíó è
Ñòðóêòóðíàÿ îðãàíèçàöèÿ, ôóíêöèÿ è äèíàìèêà ÿäåðíûõ ïîð
ñëóæèò ñâÿçóþùèì çâåíîì â ñèñòåìå ñïèö. Ýòè êîëüöà
ñîåäèíÿþò ïåðèôåðè÷åñêèå êîìïàðòìåíòû ßÏÊ ïîñðåäñòâîì âåðòèêàëüíûõ ñïèö è îáåñïå÷èâàþò, âåðîÿòíî, ñîãëàñîâàííîå ôóíêöèîíèðîâàíèå ïîðû â ïðîöåññå òðàíñïîðòà ìîëåêóë. Öåíòðàëüíûé êàíàë ßÏÊ, ðàñïîëîæåííûé âíóòðè òðàíñïîðòåðà, ìîæåò ëèáî ðàñøèðÿòüñÿ îò
10 íì â íåàêòèâíîì ñîñòîÿíèè äî 26 íì è áîëåå (Kiseleva
et al., 1998; Pante, Kann, 2002), ëèáî ñóæàòüñÿ çà ñ÷åò èçìåíåíèÿ ðàññòîÿíèÿ ìåæäó ñîñåäíèìè ñóáúåäèíèöàìè
òðàíñïîðòåðà è âíóòðåííåãî êîëüöà. Ñ÷èòàåòñÿ, ÷òî ïîðà
èìååò ïåðèôåðè÷åñêèå êàíàëû äèàìåòðîì îêîëî 5 íì
ìåæäó ñîñòàâëÿþùèìè åå êîìïàðòìåíòàìè, ÷åðåç êîòîðûå ìîãóò äèôôóíäèðîâàòü íåáîëüøèå ìîëåêóëû (Kiseleva et al., 2000). Ñîãëàñíî äàííûì ýëåêòðîííîé ìèêðîñêîïèè, êîëüöî ñïèö ÿäåðíîé ïîðû êîíòàêòèðóåò ñ
ëàìèíîé — ñåòüþ ïðîìåæóòî÷íûõ ôèëàìåíòîâ, ïîäñòèëàþùåé âíóòðåííþþ ìåìáðàíó ÿäðà (Akey, 1989; Goldberg, Allen, 1996).
Âíóòðèÿäåðíûé êîìïàðòìåíò ßÏÊ ðàñïîëàãàåòñÿ
ïîä âíóòðåííåé ÿäåðíîé ìåìáðàíîé è ñîñòîèò èç âíóòðèÿäåðíîãî êîëüöà äèàìåòðîì 120 íì, êîòîðîå òåñíî êîíòàêòèðóåò ñ ìåìáðàíîé è ñîäåðæèò âîñåìü òðåõãðàííûõ
ñóáúåäèíèö. Îíè ðàñïîëàãàþòñÿ ìåæäó îòõîäÿùèìè îò
êîëüöà 10-íàíîìåòðîâûìè ôèëàìåíòàìè, ôîðìèðóþùèìè áàñêåò-ñòðóêòóðó (ðèñ. 1, â, ã). Â íåàêòèâíîé ÿäåðíîé
ïîðå ôèáðèëëû áàñêåòà çàêðûâàþò âõîä â ïîðó, à â àêòèâíîé ïîðå îíè ôîðìèðóþò äîïîëíèòåëüíîå «òåðìèíàëüíîå» êîëüöî äèàìåòðîì îêîëî 50 íì (Goldberg, Allen, 1993; Kiseleva et al., 1996).
Ñðàâíèòåëüíûé ýëåêòðîííî-ìèêðîñêîïè÷åñêèé àíàëèç ïîêàçàë, ÷òî ßÏÊ ÿâëÿþòñÿ êîíñåðâàòèâíûìè ñòðóêòóðàìè è èìåþò ñõîäíóþ îðãàíèçàöèþ ó âûñøèõ æèâîòíûõ è ðàñòåíèé. Ïëîòíîñòü ðàñïîëîæåíèÿ ïîð â ÿäåðíîé
îáîëî÷êå âàðüèðóåò â ñðåäíåì îò 13 äî 30 ïîð íà 1 ìêì2
ÿäåðíîé îáîëî÷êè è äîñòèãàåò îò 3000 äî 5000 ïîð íà
îäíî ÿäðî â êëåòêàõ ìëåêîïèòàþùèõ, íàñåêîìûõ è àìôèáèé (Maul, 1977; Kiseleva et al., 1998). Ïðåäïîëàãàåòñÿ, ÷òî ÿäåðíûå ïîðû ÿâëÿþòñÿ óíèâåðñàëüíûìè îðãàíåëëàìè è êàæäàÿ ïîðà ìîæåò îáåñïå÷èâàòü òðàíñïîðò
ìîëåêóë êàê â ÿäðî, òàê è â öèòîïëàçìó. Èçìåíåíèå ÷èñëà ïîðîâûõ êîìïëåêñîâ â ÿäåðíîé îáîëî÷êå âûñøèõ
ýóêàðèîò ìîæåò ïðîèñõîäèòü ïðè èçìåíåíèè ôóíêöèîíàëüíîãî ñîñòîÿíèÿ êëåòîê çà ñ÷åò èõ îáðàçîâàíèÿ de novo (Bucci, Wente, 1997; Maul, 1977).  òî æå âðåìÿ èç-çà
òåñíîé ñâÿçè ñ ëàìèíîé ßÏÊ âûñøèõ ýóêàðèîò íå ìîãóò
èçìåíÿòü ñâîå ìåñòîïîëîæåíèå â ÿäåðíîé îáîëî÷êå. Â
îòëè÷èå îò âûñøèõ ýóêàðèîò íèçøèå, íàïðèìåð äðîææè,
íå èìåþò ëàìèíû. Ïî ýòîé ïðè÷èíå ÿäåðíûå ïîðû äðîææåé ìîãóò ñâîáîäíî ïåðåìåùàòüñÿ âäîëü ÿäåðíîé îáîëî÷êè, à èõ ïëîòíîñòü â ðàçëè÷íûõ ó÷àñòêàõ îáîëî÷êè
ìîæåò ñóùåñòâåííî èçìåíÿòüñÿ (Belgareh, Doye, 1993).
Òîíêîå ñòðîåíèå ßÏÊ äðîææåé áûëî èññëåäîâàíî îòíîñèòåëüíî íåäàâíî (Yang et al., 1998; Kiseleva et al., 2004a,
2004b). Áûëî ïîêàçàíî, ÷òî äèàìåòð ïîð íèçøèõ ýóêàðèîò ñîñòàâëÿåò îêîëî 100 íì, ÷òî ìåíüøå äèàìåòðà ÿäåðíûõ ïîð âûñøèõ îðãàíèçìîâ (îêîëî 120 íì), à öåíòðàëüíûé êîìïàðòìåíò ïîðû äðîææåé èìååò áîëåå ïðîñòîå
ñòðîåíèå ïî ñðàâíåíèþ ñ ïîðàìè âûñøèõ ýóêàðèîò (Yang
et al., 1998). Â òî æå âðåìÿ ñõîäñòâî ïðèíöèïîâ îáùåé
îðãàíèçàöèè ßÏÊ, à èìåííî íàëè÷èå òðåõ êîìïàðòìåíòîâ è àñèììåòðè÷íîñòü ñòðîåíèÿ ïåðèôåðè÷åñêèõ îòäåëîâ ïîðû ó íèçøèõ è âûñøèõ ýóêàðèîò, ïðåäïîëàãàåò,
÷òî èìåííî òàêîå ñòðîåíèå íåîáõîäèìî äëÿ îáåñïå÷åíèÿ
âîçìîæíîñòè äâóíàïðàâëåííîãî òðàíñïîðòà ìîëåêóë ÷åðåç ßÏÊ.
889
Áèîõèìè÷åñêèé ñîñòàâ ÿäåðíûõ ïîð
ß ä å ð í û å ï î ð û í è ç ø è õ ý ó ê à ð è î ò. Áëàãîäàðÿ
áèîõèìè÷åñêèì èññëåäîâàíèÿì ê íàñòîÿùåìó âðåìåíè
èäåíòèôèöèðîâàíû 32 íóêëåîïîðèíà äðîææåé, ñðåäè êîòîðûõ áåëîê Nup60 è 2 èíòåãðàëüíûõ áåëêà POM34p è
cdc31 îïèñàíû îòíîñèòåëüíî íåäàâíî (òàáë. 1) (Rout et
al., 2000). Nup60 ÿâëÿåòñÿ áåëêîì áàñêåò-ñòðóêòóðû
ÿäåðíîé ïîðû, POM34p ñâÿçàí ñ èíòåãðàëüíûì áåëêîì
POM152p, à cdc31p è Ndc1p ÿâëÿþòñÿ èíòåãðàëüíûìè
ìåìáðàííûìè áåëêàìè ßÏÊ. Ñëåäóåò îòìåòèòü, ÷òî íåêîòîðûå áåëêè ßÏÊ ÿâëÿþòñÿ ïîëèôóíêöèîíàëüíûìè.
Íàïðèìåð, íóêëåîïîðèíû cdc31p è Ndc1 âûÿâëÿþòñÿ êàê
â ÿäåðíûõ ïîðàõ äðîææåé, òàê è â ïîëÿðíûõ òåëüöàõ âåðåòåíà äåëåíèÿ (Chial et al., 1998; Rout et al., 2000). Áåëîê
sec13p, ÿâëÿþùèéñÿ êîìïîíåíòîì ñóáêîìïëåêñà, íåîáÒàáëèöà 1
Íóêëåîïîðèíû ÿäåðíîé ïîðû íèçøèõ (äðîææè) ýóêàðèîò
(Vasu, Forbes, 2001)
Íóêëåîïîðèí
Nup1p
Nup2p
Nup60p
N-Nup145p
Nsp1p
Gle2p
Sec13p
Seh13p
Nup49p
Nup53p
Nup84p
Nup85p
Nic96p
Nup120p
Nup133p
C-Nup145p
Nup157p
Nup188p
Nup192p
Ndc1p
Cdc31p
Pom34p
Pom152p
Nup57p
Nup59p
Nup170p
Gle1p
Nup42p
Nup82p
Nup100p
Nup116p
Nup159p
Ëîêàëèçàöèÿ â
êîìïàðòìåíòå ßÏÊ
Íàëè÷èå ïîâòîðîâ
è èõ òèï
Âíóòðèÿäåðíûé
»
»
»
Âíóòðèÿäåðíûé è
öèòîïëàçìàòè÷åñêèé
Òî æå
» »
» »
» »
» »
» »
» »
» »
» »
» »
» »
» »
» »
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ßäåðíàÿ ìåìáðàíà
» »
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Öåíòðàëüíûé
»
»
Öèòîïëàçìàòè÷åñêèé
»
»
»
»
»
FG
FG
FG
GLFG
FG
Íå îáíàðóæåíî
» »
» »
» »
» »
GLFG
Íå îáíàðóæåíî
» »
» »
» »
FG
Íå îáíàðóæåíî
» »
FG
Íå îáíàðóæåíî
» »
» »
» »
» »
» »
» »
» »
FG
Íå îáíàðóæåíî
GLFG
GLFG
FG
Í. Â. Ãóáàíîâà, Ê. Í. Ìîðîçîâà, Å. Â. Êèñåëåâà
890
Òàáëèöà 2
Íóêëåîïîðèíû ÿäåðíîé ïîðû âûñøèõ ýóêàðèîò
(Vasu, Forbes, 2001; Cronshaw et al., 2002)
Íóêëåîïîðèí
Seh1a
Gle2(Rae1)
Sec13
Nup50
Nup93
Nup96
Nup98
Nup107
Nup133
Nup153
Nup160
Nup188
Nup205
Nup155
Pom 121
Gp210
Nup45
Nup54
Nup58
Nup62
Gle1
hCG1
RanBP1
Nup88(84)
Nup214(CAN)
Nup358(RanBP2)
ALADINa
Nup35a
Nup37a
Nup43a
Nup75a
Ëîêàëèçàöèÿ
â êîìïàðòìåíòå ßÏÊ
Íàëè÷èå ïîâòîðîâ
è èõ òèï
Âíóòðèÿäåðíûé?
Âíóòðèÿäåðíûé
»
»
»
»
»
»
»
»
»
»
»
Âíóòðèÿäåðíûé è
öèòîïëàçìàòè÷åñêèé
ßäåðíàÿ ìåìáðàíà
» »
Öåíòðàëüíûé
»
»
»
Öèòîïëàçìàòè÷åñêèé
»
»
»
»
»
Íå óñòàíîâëåíî
» »
» »
» »
» »
WD
Íå îáíàðóæåíî
» »
FG
Íå îáíàðóæåíî
» »
GLFG
Íå îáíàðóæåíî
» »
FG
Íå îáíàðóæåíî
» »
» »
» »
FG
Íå îáíàðóæåíî
FG
FG
FG
FG
Íå îáíàðóæåíî
FG
Íå îáíàðóæåíî
» »
FG
FG
WD
Íå îáíàðóæåíî
WD
WD
Íå îáíàðóæåíî
õîäèìîãî äëÿ ýêñïîðòà ÐÍÊ, ó÷àñòâóåò òàêæå â ðåãóëÿöèè âíóòðèêëåòî÷íîé ñåêðåöèè (Siniossoglou et al., 1996,
2000). Êàæäûé íóêëåîïîðèí äðîææåé ïðåäñòàâëåí 8—56
êîïèÿìè íà îäíó ïîðó (Rout et al., 2000), ÷òî õîðîøî ñîâïàäàåò ñ ìîëåêóëÿðíîé ìàññîé ßÏÊ (60 ÌÄà), ïðåäñêàçàííîé íà îñíîâàíèè èçó÷åíèÿ èçîëèðîâàííûõ ïîð (Yang
et al., 1998).
30 % áåëêîâ ßÏÊ ñîäåðæàò ïîâòîðû FG (ôåíèëàëàíèí-ãëèöèí), èëè FXFG (ôåíèëàëàíèí-X-ôåíèëàëàíèí-ãëèöèí), èëè GLFG (ãëèöèí-ëåéöèí-ôåíèëàëàíèí-ãëèöèí), êîòîðûå îáúåäèíåíû â îäíî ñåìåéñòâî
FG-ïîâòîðîâ, âçàèìîäåéñòâóþùèõ ñî ñïåöèôè÷åñêèìè
òðàíñïîðòíûìè ôàêòîðàìè (Ryan, Wente, 2000). Ïîêàçàíî,
÷òî FG-ñîäåðæàùèå äîìåíû íóêëåîïîðèíîâ, âõîäÿùèõ â
ñîñòàâ òðàíñïîðòåðà, âûñòóïàþò â ïðîñâåò öåíòðàëüíîãî
êàíàëà ïîðû è, êàê ïðåäïîëàãàþò, ïðèíèìàþò àêòèâíîå
ó÷àñòèå â îáåñïå÷åíèè òðàíñïîðòà ìîëåêóë (Ryan, Wente, 2000). Èììóíîýëåêòðîííàÿ ìèêðîñêîïèÿ ïîçâîëèëà
ëîêàëèçîâàòü ìíîãèå íóêëåîïîðèíû íà îòäåëüíûõ ßÏÊ,
à áèîõèìè÷åñêèé àíàëèç ýòèõ áåëêîâ ïîêàçàë, ÷òî îíè
ñïîñîáíû ôîðìèðîâàòü êîìïëåêñû, ñîñòîÿùèå èç íåñêîëüêèõ áåëêîâ. Íåîæèäàííûì ÿâèëñÿ òîò ôàêò, ÷òî ìíîãèå íóêëåîïîðèíû, íàïðèìåð, Nsp1p, Nic96p è Nup53p,
âõîäÿò â ñîñòàâ êàê öèòîïëàçìàòè÷åñêîãî, òàê è âíóòðèÿäåðíîãî îòäåëîâ ßÏÊ (Fahrenkrog et al., 1998, 2000;
Rout et al., 2000). Òîëüêî íåáîëüøàÿ ãðóïïà íóêëåîïîðèíîâ èìååò ñïåöèôè÷åñêóþ ëîêàëèçàöèþ â ßÏÊ. Òàê, íàïðèìåð, Nup60p, Nup1p è Nup2 âûÿâëÿþòñÿ èñêëþ÷èòåëüíî íà áàñêåò-ñòðóêòóðå ïîðû, à áåëîê Nup145Np, ñîäåðæàùèé GLFG-ïîâòîð, ëîêàëèçóåòñÿ ñ ÿäåðíîé
ñòîðîíû, áëèæå ê öåíòðàëüíîìó êàíàëó ïîðû (Hood et
al., 2000; Solsbacher et al., 2000). Åñëè ó äðîææåé ìíîãèå
íóêëåîïîðèíû ïðèñóòñòâóþò êàê íà âíóòðèÿäåðíîé, òàê
è íà öèòîïëàçìàòè÷åñêîé ñòîðîíå ïîðû, òî áîëüøèíñòâî
íóêëåîïîðèíîâ â ßÏÊ âûñøèõ ýóêàðèîò èìåþò áîëåå
ñïåöèôè÷åñêóþ ëîêàëèçàöèþ íà îòäåëüíûõ êîìïîíåíòàõ
ßÏÊ (Vasu, Forbes, 2001).
ß ä å ð í û å ï î ð û â û ñ ø è õ ý ó ê à ð è î ò. Ñ ïîìîùüþ
ìîëåêóëÿðíî-áèîëîãè÷åñêèõ, áèîõèìè÷åñêèõ, öèòîëîãè÷åñêèõ è èììóíîãèñòîõèìè÷åñêèõ ìåòîäîâ â ÿäåðíûõ ïîðàõ ó ïîçâîíî÷íûõ îáíàðóæåíû 31 íóêëåîïîðèí (òàáë. 2)
è 18 áåëêîâ, îòíîñÿùèõñÿ ê êëàññó ßÏÊ-àññîöèèðîâàííûõ áåëêîâ (Vasu, Forbes, 2001; Cronshaw et al., 2002). Ïîêàçàíî, ÷òî íóêëåîïîðèíû âûñøèõ îðãàíèçìîâ ìîãóò ôîðìèðîâàòü 12 ñóáêîìïëåêñîâ, íà êîòîðûå ïîðà ðàçáèðàåòñÿ
â ïðîôàçå ìèòîçà è èç êîòîðûõ îíà ñîáèðàåòñÿ â òåëîôàçå
(Matsuoka et al., 1999; Smythe et al., 2000). Ïðåäïîëàãàþò,
÷òî íîâûå ïîðû ìîãóò ñîáèðàòüñÿ òàêæå èç ýòèõ ñóáêîìïëåêñîâ âî âðåìÿ S-ôàçû, êîãäà êîëè÷åñòâî ïîð ó ïîçâîíî÷íûõ óäâàèâàåòñÿ (Vasu, Forbes, 2001).
 ýêñïåðèìåíòàõ ñ èñïîëüçîâàíèåì GFP-(green fluorescent protein)-ìå÷åííûõ áåëêîâ è èììóíîýëåêòðîííîé
ìèêðîñêîïèè áûëî óñòàíîâëåíî, ÷òî âíóòðèÿäåðíûé
êîìïàðòìåíò ßÏÊ ñîäåðæèò Nup153, Nup98/Gle2, Nup50
è íîâûé ñóáêîìïëåêñ Nup107-160, êóäà âõîäÿò Nup160/
Nup133/ Nup96/ Nup107 è, âîçìîæíî, ãîìîëîã äðîææåâîãî áåëêà seh1 (ðèñ. 2) (Vasu, Forbes, 2001; Cronshaw et al.,
2002). Ñóùåñòâóåò ïðåäïîëîæåíèå î òîì, ÷òî ñóáêîìïëåêñ Nup107-160, âçàèìîäåéñòâóÿ ñ õðîìàòèíîì, èãðàåò
îïðåäåëåííóþ ðîëü â îáðàçîâàíèè ßÏÊ â ñîñòàâå ÿäåðíîé îáîëî÷êè. Ê êîìïîíåíòàì öåíòðàëüíîãî îòäåëà ßÏÊ
îòíîñÿò êîìïëåêñû Nup62/ Nup58/ Nup54/ Nup45, Nup93,
Nup205-Nup188 è áåëîê Nup155 (Vasu, Forbes, 2001).
Öèòîïëàçìàòè÷åñêèé îòäåë ïîðû ñîäåðæèò Nup214,
Nup88(84), Nup358 è RanBP1 (Ryan, Wente, 2000). Ñ íóêëåîïîðèíîì Nup358 ñâÿçûâàåòñÿ óáèêâèòèí-ïîäîáíûé
ìîäèôèêàòîð SUMO-1, êîòîðûé òàêæå îáðàçóåò ñâÿçü ñ
RanGAP (áåëîê, àêòèâèðóþùèé ÃÒÔàçó Ran) (Melchior,
2000).
Èíòåãðàëüíûå ìåìáðàííûå áåëêè gp210 è Pom121
âûïîëíÿþò ôóíêöèþ çàêðåïëåíèÿ ßÏÊ â ìåìáðàíå. Áåëîê gp210 ñîäåðæèò áîëüøîé äîìåí, îáðàùåííûé â ïåðèíóêëåàðíîå ïðîñòðàíñòâî, è êîðîòêèé, òî÷íàÿ ëîêàëèçàöèÿ êîòîðîãî ïîêà íå óñòàíîâëåíà. Íóêëåîïîðèí
Pom121 ñîäåðæèò FG-ïîâòîðû â áîëüøîì öèòîïëàçìàòè÷åñêîì äîìåíå, à êîðîòêèé äîìåí ýòîãî áåëêà îáðàùåí â
ïðîñâåò ìåæäó ìåìáðàíàìè ÿäåðíîé îáîëî÷êè (Stoffler et
al., 1999; Ryan, Wente, 2000). Òàê æå êàê è ó íèçøèõ ýóêàðèîò, êàæäûé íóêëåîïîðèí âûñøèõ îðãàíèçìîâ ìîæåò
áûòü ïðåäñòàâëåí â êîëè÷åñòâå îò 8 äî 56 êîïèé, ÷òî äàåò
â ñóììå îêîëî 1000 áåëêîâ íà îäíó ïîðó (Vasu, Forbes,
2001).
Áîëüøîå âíèìàíèå óäåëÿåòñÿ èçó÷åíèþ áåëêà Nup153,
âõîäÿùåãî â ñîñòàâ âíóòðèÿäåðíîãî è, âîçìîæíî, òåðìè-
Ñòðóêòóðíàÿ îðãàíèçàöèÿ, ôóíêöèÿ è äèíàìèêà ÿäåðíûõ ïîð
íàëüíîãî êîëüöà áàñêåò-ñòðóêòóðû; Nup153, êàê ïðåäïîëàãàþò, ó÷àñòâóåò â èíèöèàöèè ñáîðêè ÿäåðíîé îáîëî÷êè, ïðåäøåñòâóþùåé ôîðìèðîâàíèþ ßÏÊ â ìèòîçå
(Smythe et al., 2000). Óñòàíîâëåíî, ÷òî Nup153 íåîáõîäèì êàê äëÿ èìïîðòà, òàê è äëÿ ýêñïîðòà ìîëåêóë (Bastor
et al., 1996; Ullman et al., 1999), îí âûÿâëÿåòñÿ â ðàçíûõ
ó÷àñòêàõ ßÏÊ è, âîçìîæíî, ÿâëÿåòñÿ «øàòëèíã»-áåëêîì,
ïåðåìåùàþùèìñÿ âäîëü âñåé ïîðû (Nakielny et al.,
1999).
Áåëîê Nup98 òàêæå âõîäèò â ñîñòàâ áàñêåò-ñòðóêòóðû ïîðû è âîâëå÷åí â ýêñïîðò ÐÍÊ (Powers et al., 1997;
Ryan, Wente, 2000). N-êîíöåâîé äîìåí ýòîãî áåëêà ñîäåðæèò GLFG-ïîâòîð, ñâÿçûâàþùèé òðàíñïîðòíûå ôàêòîðû Rael/Gle2, TAP è Crm1, â òî âðåìÿ êàê C-êîíöåâîé
äîìåí ñâÿçûâàåòñÿ ñ êîìïëåêñîì Nup160 (Vasu, Forbes,
2001). Ïðåäïîëàãàåòñÿ, ÷òî Nup98 è òåñíî âçàèìîäåéñòâóþùèé ñ íèì Nup96, âûÿâëÿåìûå â áàñêåò-ñòðóêòóðå
ßÏÊ, ìîãóò ÿâëÿòüñÿ ïðîèçâîäíûìè Nup145p äðîææåé,
êîòîðûé â õîäå ýâîëþöèè ðàçäåëèëñÿ íà äâà áåëêà (Teixeira et al., 1999). Èíòåðåñíî, ÷òî GLFG-ïîâòîð Nup98
ñëóæèò ìèøåíüþ äëÿ âèðóñà ñòîìàòèòà (VSV) (Petersen
et al., 2000). Ïðåäïîëàãàþò, ÷òî áåëîê ìàòðèêñà VSV ìîæåò ñâÿçûâàòüñÿ ñ Nup98 è íàðóøàòü ýêñïîðò ìÐÍÊ è
èìïîðò ÿäåðíûõ áåëêîâ õîçÿèíà (Von Kobbe et al., 2000).
Îòíîñèòåëüíî íåäàâíî áûëè îòêðûòû äâà íîâûõ íóêëåîïîðèíà ïîçâîíî÷íûõ — Nup50 (Guan et al., 2000;
Smitherman et al., 2000) è Nup188 (Matsuoka et al., 1999;
Stoffer et al., 1999). Nup50 ëîêàëèçîâàí â áàñêåò-ñòðóêòóðå ÿäåðíîé ïîðû è ñîäåðæèò FG-ïîâòîð. Ýòîò áåëîê ïðèíèìàåò ó÷àñòèå â ýêñïîðòå, îñóùåñòâëÿåìîì òðàíñïîðòíûì ôàêòîðîì Crm1, êîòîðûé ñâÿçûâàåòñÿ ñ ìîëåêóëàìè, ñîäåðæàùèìè NES-(nuclear export sequense)-ïîñëåäîâàòåëüíîñòü, íî íå ïðèíèìàåò ó÷àñòèÿ â èìïîðòå
áåëêîâ. Áèîõèìè÷åñêèå èññëåäîâàíèÿ ïîäòâåðäèëè,
÷òî Nup50 ñîäåðæèò ðåöåïòîð ðàííåãî ñâÿçûâàíèÿ ñ
NES-êîìïëåêñîì è âçàèìîäåéñòâóåò ñ ðàñïîëîæåííûìè
ðÿäîì ñ íèì Nup153 è èíãèáèòîðîì êëåòî÷íîãî öèêëà p27.
Ñëåäóåò äîáàâèòü, ÷òî èììóíîôëóîðåñöåíòíûé àíàëèç
áåëêîâ Nup50, Nup96, Nup98 è Nup153 âûÿâèë òàêæå èõ
ëîêàëèçàöèþ âíóòðè ÿäðà, îäíàêî äî ñèõ ïîð îñòàåòñÿ íåÿñíûì, âûïîëíÿþò ëè ýòè áåëêè êàêóþ-ëèáî äîïîëíèòåëüíóþ ðîëü íåïîñðåäñòâåííî â ÿäðå (Vasu, Forbes, 2001).
Èññëåäîâàíèÿ ïîñëåäíèõ ëåò âûÿâèëè åùå 6 íóêëåîïîðèíîâ, ïîëó÷èâøèõ íàçâàíèÿ Nup35, Seh1, Nup75,
Nup37, Nup43 è ALADIN, âçàèìîäåéñòâóþùèõ ñ àíòèòåëàìè mAb414, êîòîðûå îêðàøèâàþò è äðóãèå áåëêè ßÏÊ
(Gronshaw et al., 2002). Ýòè 6 áåëêîâ äîñòàòî÷íî õîðîøî
îõàðàêòåðèçîâàíû, íî ïîêà íå óñòàíîâëåíî, â êàêîì êîìïàðòìåíòå ßÏÊ îíè ëîêàëèçîâàíû. Àíàëèç èõ àìèíîêèñëîòíîé ïîñëåäîâàòåëüíîñòè ïîêàçàë, ÷òî áåëêè Nup75,
Nup35 è Seh1 èìåþò ãîìîëîãèþ ñ íåêîòîðûìè èçâåñòíûìè íóêëåîïîðèíàìè. Òàê, Nup75 èìååò 19 % ãîìîëîãèè ñ
Nup85 äðîææåé, Nup35 íà 21 % èäåíòè÷åí Nup53p äðîææåé, à Seh1 èìååò âûñîêóþ ãîìîëîãèþ ñ äðîææåâûì íóêëåîïîðèíîì Seh1p (30 %) è ñ íóêëåîïîðèíîì ïîçâîíî÷íûõ Sec13R (34 %) (Cronshaw et al., 2002).
 ñîñòàâå She1-áåëêà îáíàðóæåíî 6 WD-ïîâòîðîâ
(WD — äèïåïòèäû òðèïòîôàíà è àñïàðòàòà), îí ÿâëÿåòñÿ
îäíèì èç êàíäèäàòîâ â ãîìîëîãè ÷åëîâå÷åñêîìó íóêëåîïîðèíó Sec1p êàê ïî ïîñëåäîâàòåëüíîñòè àìèíîêèñëîò
(50 % èäåíòè÷íîñòè), òàê è ôóíêöèîíàëüíî (Cronshaw et
al., 2002). Áèîõèìè÷åñêèé àíàëèç òàêæå ïîêàçàë, ÷òî êðîìå Seh1 åùå 3 íóêëåîïîðèíà — Nup37, Nup43 è ALADIN — ñîäåðæàò WD-ïîâòîðû, êîòîðûå âñòðå÷àþòñÿ â
ðàçëè÷íûõ ýóêàðèîòè÷åñêèõ áåëêàõ, ñîñòàâëÿþùèõ îñî-
891
Ðèñ. 2. Áåëêîâûé ñîñòàâ ðàçëè÷íûõ êîìïàðòìåíòîâ ÿäåðíîãî
ïîðîâîãî êîìïëåêñà (ìîäèôèöèðîâàíà èç: Vasu, Forbes, 2001).
ßÎ — ÿäåðíàÿ îáîëî÷êà.
áîå ñóáñåìåéñòâî. Áåëêè ýòîãî ñóáñåìåéñòâà èìåþò
ñõîäíóþ ïîâåðõíîñòü è, âîçìîæíî, îáùèõ ïàðòíåðîâ äëÿ
ñâÿçûâàíèÿ (Smith et al., 1999). Ýòî ïîñëóæèëî îñíîâàíèåì äëÿ ïðåäïîëîæåíèÿ î âîçìîæíîì ó÷àñòèè íóêëåîïîðèíîâ, ñîäåðæàùèõ WD-ïîâòîðû, â ñáîðêå êðóïíûõ
ìóëüòèáåëêîâûõ êîìïëåêñîâ ßÏÊ, êîòîðûå âûÿâëÿþòñÿ
â ìèòîçå (Cronshaw et al., 2002). Ïîñêîëüêó Nup37,
Nup43 è ALADIN íå èìåþò ãîìîëîãîâ ñðåäè äðîææåâûõ
íóêëåîïîðèíîâ, ïðåäïîëàãàåòñÿ, ÷òî îíè âûïîëíÿþò ñïåöèôè÷åñêóþ ôóíêöèþ â ßÏÊ ó âûñøèõ ýóêàðèîò (Cronshaw et al., 2002).  ïîñëåäíåå âðåìÿ ñ èñïîëüçîâàíèåì
FRAP-ìåòîäà (Fluorescence Recover After Photobleaching)
áûëî ïîêàçàíî, ÷òî íóêëåîïîðèíû âûñøèõ ýóêàðèîò ïî
äëèòåëüíîñòè èõ âçàèìîäåéñòâèÿ ñ ßÏÊ ìîæíî ðàçäåëèòü íà òðè ãðóïïû: 1) ñòàáèëüíûå, êîòîðûå îáíîâëÿþòñÿ çà 35 ÷ è áîëåå, ñîñòàâëÿþò êàðêàñ ßÏÊ; 2) òå, êîòîðûå îáíîâëÿþòñÿ çà 2.5—30.0 ÷ è, âåðîÿòíî, àêòèâíî
ó÷àñòâóþò â òðàíñïîðòå ìîëåêóë; 3) áåëêè, îáíîâëÿþùèåñÿ â òå÷åíèå íåñêîëüêèõ ñåêóíä èëè ìèíóò, îñíîâíàÿ
ôóíêöèÿ êîòîðûõ íå ñâÿçàíà ñ ßÏÊ (Rabut et al., 2004).
Ìåõàíèçìû òðàíñïîðòà ìîëåêóë
÷åðåç ÿäåðíóþ ïîðó
Èçâåñòíî, ÷òî êàæäóþ ñåêóíäó ßÏÊ ìîæåò îáåñïå÷èâàòü òðàíñïîðò äî 400 ìîëåêóë è áîëåå (Macara, 2001).
Èîíû è ìîëåêóëû ìåíüøå 9 íì â äèàìåòðå ìîãóò ñâîáîäíî (ïàññèâíî) äèôôóíäèðîâàòü ÷åðåç ïåðèôåðè÷åñêèå
êàíàëû è öåíòðàëüíûé êàíàë ïîðû, êîòîðûé â íåàêòèâíîì ñîñòîÿíèè èìååò äèàìåòð îêîëî 10 íì. Áîëåå êðóïíûå îáðàçîâàíèÿ, òàêèå, íàïðèìåð, êàê ðèáîñîìíûå
ñóáúåäèíèöû, èìåþùèå äèàìåòð îêîëî 20 íì, áåëêè è
ÐÍÏ-÷àñòèöû, òðàíñïîðòèðóþòñÿ ÷åðåç ßÏÊ àêòèâíî,
ò. å. ñ çàòðàòîé ýíåðãèè. Ýíåðãåòè÷åñêè-çàâèñèìûé òðàíñïîðò îáåñïå÷èâàåòñÿ ìàëîé ÃÒÔ-àçîé Ran, ñóùåñòâóþùåé â ÃÒÔ- è ÃÄÔ-ñâÿçàííîé ôîðìàì. Ran-ÃÒÔ îáíàðó-
892
Í. Â. Ãóáàíîâà, Ê. Í. Ìîðîçîâà, Å. Â. Êèñåëåâà
Ðèñ. 3. Ñõåìà, äåìîíñòðèðóþùàÿ ôóíêöèîíàëüíóþ ðîëü Ran-áåëêà â ðåãóëÿöèè ÿäåðíî-öèòîïëàçìàòè÷åñêîãî òðàíñïîðòà (ìîäèôèöèðîâàíà èç: Clarke, Zhang, 2001).
Ran-áåëîê ïîñòîÿííî êóðñèðóåò ÷åðåç ÿäåðíûå ïîðîâûå êîìïëåêñû, íî íàêàïëèâàåòñÿ ïðåèìóùåñòâåííî â ÿäðå çà ñ÷åò åãî àêòèâíîãî èìïîðòà. Âûñîêàÿ êîíöåíòðàöèÿ Ran-ÃÒÔ â íóêëåîïëàçìå ñîçäàåòñÿ çà ñ÷åò êàòàëèòè÷åñêîé àêòèâíîñòè áåëêà RCC1, ñâÿçàííîãî ñ õðîìàòèíîì. Ran-ÃÒÔ âûçûâàåò
äèññîöèàöèþ èìïîðòèðóåìîãî êîìïëåêñà, ñîäåðæàùåãî áåëîê ñ ïîñëåäîâàòåëüíîñòüþ NLS (nuclear localization sequence), çà ñ÷åò åãî ñâÿçûâàíèÿ ñ èìïîðòèíîì b. Ñâÿçûâàíèå Ran-ÃÒÔ ñ ýêñïîðòèíîì/Crm1 â ÿäðå ñïîñîáñòâóåò ñáîðêå ýêñïîðòèðóåìîãî êîìïëåêñà, ñîäåðæàùåãî áåëîê ñ ïîñëåäîâàòåëüíîñòüþ NES (nuclear export sequence).  öèòîïëàçìå Ran-ÃÒÔ ïåðåõîäèò â Ran-ÃÄÔ è ôîñôàòíóþ ãðóïïó (Ôi) ïîä äåéñòâèåì Ran-ÃÒÔàçû, êîòîðàÿ àêòèâèðóåòñÿ RanGAP è RanBP1, â ðåçóëüòàòå ÷åãî ýêñïîðòèðóåìûé êîìïëåêñ îñâîáîæäàåòñÿ.
æèâàåòñÿ ïðåèìóùåñòâåííî â ÿäðå è îáðàçóåòñÿ èç
Ran-ÃÄÔ ïðè ó÷àñòèè ìèòîòè÷åñêîãî ôàêòîðà RCC1 (regulator of chromosome condensation), ñâÿçàííîãî ñ õðîìàòèíîì (Bischoff, Ponstingl, 1991). Ran-ÃÄÔ ïðèñóòñòâóåò
â îñíîâíîì â öèòîïëàçìå è ôîðìèðóåòñÿ ïðè ãèäðîëèçå
ÃÒÔ ñ ó÷àñòèåì ñïåöèôè÷åñêîãî äëÿ Ran-ÃÒÔàçû àêòèâèðóþùåãî áåëêà RanGAP1 (GTPase-activating protein) è
åãî àêòèâàòîðà RanBP1 (Ran-binding proteins) (ðèñ. 3)
(Bischoff et al., 1994).
Ïîêàçàíî, ÷òî åäèíè÷íûé èìïîðò ìîëåêóë ÷åðåç
ßÏÊ â óñëîâèÿõ in vitro íå òðåáóåò çàòðàòû ýíåðãèè, òîãäà êàê ïðè ìíîæåñòâåííîì èìïîðòå è ýêñïîðòå íåîáõîäèìî ïîòðåáëåíèå ýíåðãèè, îáåñïå÷èâàåìîé ãèäðîëèçîì Ran-ÃÒÔ (Englmeier et al., 1999; Ribbeck et al., 1999).
Ãðàäèåíò êîíöåíòðàöèè Ran-ÃÒÔ/Ran-ÃÄÔ îáåñïå÷èâàåò íàïðàâëåíèå ÿäåðíî-öèòîïëàçìàòè÷åñêîãî òðàíñïîðòà
ìîëåêóë è ïîääåðæèâàåòñÿ ïðè ïîìîùè òðàíñïîðòíîãî
ôàêòîðà NTF2 (nuclear-transport factor 2, p10 èëè p15)
(Ribbeck et al., 1998; Smith et al., 1998). Ýòîò áåëîê ñïåöèôè÷åñêè ñâÿçûâàåòñÿ ñ Ran-ÃÄÔ è íóêëåîïîðèíîì Nup62,
à çàòåì ïåðåìåùàåòñÿ ÷åðåç ßÏÊ â ÿäðî, ãäå RCC1 çàïóñêàåò ðàçáîðêó Ran-ÃÄÔ/NTF2-êîìïëåêñà è ïåðåâîäèò
Ran-ÃÄÔ â Ran-ÃÒÔ-ôîðìó (Clarkson et al., 1996; Sreward et al., 1998). NTF2 çà ñ÷åò ñâîèõ ìàëûõ ðàçìåðîâ
(15 êÄà) ìîæåò áûñòðî äèôôóíäèðîâàòü ÷åðåç ßÏÊ, ñïîñîáåí ñâÿçûâàòüñÿ îäíîâðåìåííî ñ äâóìÿ ìîëåêóëàìè
Ran-ÃÄÔ è ïåðåíîñèòü èõ â ÿäðî, îïòèìèçèðóÿ ñêîðîñòü
òðàíñïîðòà ìîëåêóë (Steward et al., 1998).
È ì ï î ð ò ì î ë å ê ó ë. Áëàãîäàðÿ ìîëåêóëÿðíî-áèîëîãè÷åñêèì è áèîõèìè÷åñêèì èññëåäîâàíèÿì ìåõàíèçìà
òðàíñïîðòà ìîëåêóë ÷åðåç ßÏÊ ê íàñòîÿùåìó âðåìåíè
ïîêàçàíî, ÷òî ñïåöèôè÷åñêèå áåëêè — èìïîðòèíû è ýêñïîðòèíû — ñâÿçûâàþòñÿ ñ ñèãíàëüíîé ïîñëåäîâàòåëüíîñòüþ òðàíñïîðòèðóåìîé ìîëåêóëû è îñóùåñòâëÿþò åå
èìïîðò èëè ýêñïîðò èç ÿäðà (ðèñ. 3). Êëþ÷åâîé õàðàêòåðèñòèêîé âñåõ áåëêîâ — ïåðåíîñ÷èêîâ èìïîðòèðóåìûõ
ìîëåêóë — ÿâëÿåòñÿ èõ ñïîñîáíîñòü ôîðìèðîâàòü êîìïëåêñ ñ Ran-ÃÒÔ/ÃÄÔ è òðàíñïîðòèðóåìîé ìîëåêóëîé
(Macara, 2001). Ñîãëàñíî êëàññè÷åñêîé ñõåìå èìïîðòà,
áåëêè, ñîäåðæàùèå NLS-ïîñëåäîâàòåëüíîñòü (nuclear localization sequence), ÿâëÿþòñÿ ñóáñòðàòîì, ñ êîòîðûì
ñâÿçûâàåòñÿ èìïîðòèí á (ñîãëàñíî äðóãîé íîìåíêëàòóðå,
êàðèîôåðèí á) (Moroianu et al., 1995). Çàòåì èìïîðòèí â
(p 97 èëè êàðèîôåðèí â) ñâÿçûâàåòñÿ ñ N-êîíöåâûì äîìåíîì èìïîðòèíà á è îáåñïå÷èâàåò ïðèêðåïëåíèå ñôîðìèðîâàâøåãîñÿ êîìïëåêñà NLS-ñóáñòðàò—èìïîðòèíû
á/â ê öèòîïëàçìàòè÷åñêîìó êîìïàðòìåíòó ßÏÊ. Äàëåå
ýòîò êîìïëåêñ òðàíñïîðòèðóåòñÿ âìåñòå ñ Ran-ÃÄÔ ÷åðåç ßÏÊ â ÿäðî, ãäå ðàñïàäàåòñÿ íà ñîñòàâíûå êîìïîíåíòû.  îñâîáîæäåíèè èìïîðòèðóåìîé ìîëåêóëû ïðèíèìàåò ó÷àñòèå Ran-ÃÒÔ, êîòîðûé ñâÿçûâàåòñÿ ñ èìïîðòèíîì
â è çàêàí÷èâàåò òåì ñàìûì ïðîöåññ èìïîðòà (Clarke,
Zhang, 2001).
Ïîêàçàíî, ÷òî èìïîðòèí â áåç ó÷àñòèÿ èìïîðòèíà á
ìîæåò ôîðìèðîâàòü êîìïëåêñû íåïîñðåäñòâåííî ñ
òðàíñïîðòèðóåìûì áåëêîì (Palmeri et al., 1999), à òàêæå
ñ áåëêîì ñíóðïîðòèíîì (snurportin ), ñâÿçûâàþùèìñÿ ñî
ñïëàéñîñîìíîé ÐÍÊ (Görlich et al., 1994), áåëêîì XRIPá,
âçàèìîäåéñòâóþùèì ñ ÄÍÊ-õåëèêàçàìè (Jullien et al.,
1999), è ñ èìïîðòèíîì 7, êîòîðûé îáåñïå÷èâàåò èìïîðò
ãèñòîíà H1 (Taura et al., 1998; Jakel et al., 1999). Óñòàíîâëåíî òàêæå, ÷òî èìïîðòèí â îáåñïå÷èâàåò èìïîðò ðåãó-
Ñòðóêòóðíàÿ îðãàíèçàöèÿ, ôóíêöèÿ è äèíàìèêà ÿäåðíûõ ïîð
ëÿòîðíûõ áåëêîâ âèðóñà èììóíîäåôèöèòà ÷åëîâåêà Tat è
Rev (Truant et al., 1999). Ýòî îáóñëîâëåíî íàëè÷èåì ó
ýòèõ áåëêîâ îñîáîé ïîñëåäîâàòåëüíîñòè, ãîìîëîãè÷íîé
äîìåíó èìïîðòèíà á, ñâÿçûâàþùåìóñÿ ñ èìïîðòèíîì â.
Èìïîðòèí á êîäèðóåòñÿ ñ îäíèì ãåíîì ó äðîææåé, íî ñóùåñòâóåò â øåñòè èçîôîðìàõ, êàæäàÿ èç êîòîðûõ îòëè÷àåòñÿ ïî ïîñëåäîâàòåëüíîñòè C-êîíöåâîãî äîìåíà, ÷òî
õàðàêòåðíî è äëÿ ìëåêîïèòàþùèõ. Êàæäàÿ èç ýòèõ èçîôîðì îïîçíàåò ñèãíàëüíûå ïîñëåäîâàòåëüíîñòè èìïîðòèðóåìûõ áåëêîâ ñ ðàçëè÷íûì ñðîäñòâîì, õîòÿ èçâåñòíî,
÷òî âñå èçîôîðìû îäèíàêîâî ñâÿçûâàþòñÿ ñ âèðóñîì
SV40 (Tsuji et al., 1997; Welch et al., 1999). Èçâåñòíî, ÷òî
èìïîðòèí â ñâÿçûâàåòñÿ ñ íóêëåîïîðèíàìè: Nup358
(RanBP2 — â äðóãîé íîìåíêëàòóðå), âõîäÿùèì â ñîñòàâ
öèòîïëàçìàòè÷åñêèõ ôèáðèëë ßÏÊ, p62 — êîìïîíåíòîì
öåíòðàëüíîãî êàíàëà ÿäåðíûõ ïîð, à òàêæå Nup153, ëîêàëèçóþùèìñÿ â áàñêåò-ñòðóêòóðå ßÏÊ, è, òàêèì îáðàçîì,
ïðèíèìàåò íåïîñðåäñòâåííîå ó÷àñòèå â òðàíñïîðòå (Allen et al., 2000; Ryan, Wenter, 2000).
Êðîìå êëàññè÷åñêîé NLS-ïîñëåäîâàòåëüíîñòè â ñîñòàâå ãåòåðîãåííûõ ÐÍÊ-ñâÿçûâàþùèõñÿ áåëêîâ A1 è A2
(hnRNP A1 è hnRNP A2), êîòîðûå êóðñèðóþò ìåæäó ÿäðîì è öèòîïëàçìîé, íî ïðåèìóùåñòâåííî âûÿâëÿþòñÿ â
ÿäðå, áûëà îáíàðóæåíà ïîñëåäîâàòåëüíîñòü, íàçâàííàÿ
M9 (Siomi, Dreyfuss, 1995). Äàííàÿ ïîñëåäîâàòåëüíîñòü
îáíàðóæåíà â C-êîíöåâîì äîìåíå ÐÍÊ-ñâÿçûâàþùèõñÿ
áåëêîâ è ñîñòîèò èç 38 àìèíîêèñëîò (Michael et al., 1995).
M9 çíà÷èòåëüíî îòëè÷àåòñÿ îò êëàññè÷åñêîé NLS-ïîñëåäîâàòåëüíîñòè ïî àìèíîêèñëîòíîìó ñîñòàâó, íî ÿâëÿåòñÿ
íåîáõîäèìîé è äîñòàòî÷íîé äëÿ èìïîðòà â ÿäðî äàííîãî
ñåìåéñòâà áåëêîâ (Siomi, Dreyfuss, 1995). Óäèâèòåëüíûì
îêàçàëñÿ òîò ôàêò, ÷òî ýòà æå ïîñëåäîâàòåëüíîñòü ñëóæèò è äëÿ ýêñïîðòà hnRNP A1-áåëêà â öèòîïëàçìó (Michael et al., 1995), ÷òî, êàê áûëî ïîêàçàíî, âîçìîæíî òîëüêî ïðè íàëè÷èè åãî ñâÿçè ñ ìÐÍÊ (Weighardt et al., 1995).
Åäèíñòâåííûì èçâåñòíûì ê íàñòîÿùåìó âðåìåíè
òðàíñïîðòíûì ôàêòîðîì, ñïîñîáíûì ñâÿçûâàòüñÿ ñ ïîñëåäîâàòåëüíîñòüþ M9, ÿâëÿåòñÿ òðàíñïîðòèí 1 (áåëîê ñ
ìîë. ìàññîé 101 êÄà, èäåíòè÷íûé íà 24 % èìïîðòèíó â),
êîòîðûé ïåðåíîñèò áåëêè, ñîäåðæàùèå M9, â ÿäðî, íå âîâëåêàÿ äîïîëíèòåëüíûõ ôàêòîðîâ (Cordes et al., 1997).
Âçàèìîäåéñòâóÿ ñ RanÃÒÔ âíóòðè ÿäðà, òðàíñïîðòèí 1
ìåíÿåò ñâîþ êîíôîðìàöèþ, â ðåçóëüòàòå ÷åãî ïðîèñõîäèò îñâîáîæäåíèå òðàíñïîðòèðóåìîé ìîëåêóëû. Çàòåì
êîìïëåêñ òðàíñïîðòèí 1/Ran-ÃÒÔ ïåðåìåùàåòñÿ â öèòîïëàçìó, ãäå â ðåçóëüòàòå ãèäðîëèçà ÃÒÔ îí äèññîöèèðóåò íà îòäåëüíûå êîìïîíåíòû. Âçàèìîäåéñòâóåò ëè òðàíñïîðòèí 1 ñ òåìè æå áåëêàìè ÿäåðíîé ïîðû, ÷òî è èìïîðòèí â, èëè ñ äðóãèìè íóêëåîïîðèíàìè, îñòàåòñÿ ïîêà
íåèçâåñòíûì (Cordes et al., 1997).
Ý ê ñ ï î ð ò ì î ë å ê ó ë. Äëÿ ýêñïîðòà ìîëåêóë òðåáóåòñÿ Ran-ÃÒÔ, êîòîðûé îáåñïå÷èâàåò ñáîðêó ýêñïîðòèðóåìîãî êîìïëåêñà â ÿäðå, à òàêæå ñïîñîáñòâóåò åãî äèññîöèàöèè â öèòîïëàçìå çà ñ÷åò ãèäðîëèçà Ran-ÃÄÔ (Macara, 2001). Íàèáîëåå õîðîøî èçó÷åííûìè ðåãóëÿòîðàìè ýêñïîðòà ìîëåêóë ÿâëÿþòñÿ ýêñïîðòèí Crm1 (exportin èëè Xpo 1), îáåñïå÷èâàþùèé ýêñïîðò áåëêîâ,
Tap-1/Mex67, íåîáõîäèìûé äëÿ ýêñïîðòà ìÐÍÊ, è êàëðåòèêóëèí (calreticulin), ñïîñîáñòâóþùèé ýêñïîðòó ñòåðîèäíûõ ðåöåïòîðîâ èç ÿäðà (Macara, 2001). Âñå ýòè ðåãóëÿòîðû îïîçíàþò êîðîòêèå ëåéöèí-áîãàòûå NES-ðàéîíû
òðàíñïîðòèðóåìûõ ìîëåêóë è ñâÿçûâàþòñÿ ñ íèìè. Ñëåäóåò îòìåòèòü, ÷òî áåëêè, íåñóùèå NES-ïîñëåäîâàòåëüíîñòè, â ñâîþ î÷åðåäü ñïîñîáíû âçàèìîäåéñòâîâàòü ñ
ðàçëè÷íûìè âèäàìè ÐÍÊ (Macara, 2001). Êîìïëåêñ
893
NES-ñóáñòðàò/Crm1/Ran-ÃÒÔ ýêñïîðòèðóåòñÿ ñ ÿäåðíîé
íà öèòîïëàçìàòè÷åñêóþ ñòîðîíó ßÏÊ, ãäå íóêëåîïîðèí
RanBP1 îáåñïå÷èâàåò ñâÿçûâàíèå êîìïëåêñà ñ ÿäåðíîé
ïîðîé (Kehlenbach et al., 1999). RanGAP, òàêæå ëîêàëèçóþùèéñÿ íà öèòîïëàçìàòè÷åñêîé ñòîðîíå ïîðû (Matunis
et al., 1996; Mahajan et al., 1997), àêòèâèðóåò ÃÒÔàçíóþ
àêòèâíîñòü Ran, èñïîëüçóÿ RanBP1 êàê êîôàêòîð, â ðåçóëüòàòå ÷åãî Ran-ÃÒÔ ïåðåõîäèò â Ran-ÃÄÔ (Bischoff et
al., 1995). Òàê êàê Ran-ÃÄÔ èìååò íèçêîå ñðîäñòâî ê
Crm1, îí áûñòðî äèññîöèèðóåò èç êîìïëåêñà, ÷òî âûçûâàåò îñâîáîæäåíèå NES-áåëêà îò Crm1, ïîñëå ÷åãî
îñâîáîæäåííûé Crm1 âîçâðàùàåòñÿ â ÿäðî (ðèñ. 3). Èçó÷åíèå ÿäåðíî-öèòîïëàçìàòè÷åñêîãî òðàíñïîðòà âûÿâèëî
åùå îäèí êîôàêòîð, ó÷àñòâóþùèé â Crm1-îïîñðåäîâàííîì òðàíñïîðòå. Ýòî áåëîê Nxt1 (p15) (íà ðèñ. 3 íå ïîêàçàí), êîòîðûé ñâÿçûâàåòñÿ íåïîñðåäñòâåííî ñ Crm1 è
âìåñòå ñ RanBP3 ñòàáèëèçèðóåò ýêñïîðòèðóåìûé êîìïëåêñ, à òàêæå ñïîñîáñòâóåò çàêëþ÷èòåëüíûì ýòàïàì
Crm1-çàâèñèìîãî ýêñïîðòà (Black et al., 2001; Hofmann et
al., 2001).
Äðóãîé áåëîê, ó÷àñòâóþùèé â ýêñïîðòå, — ýêñïîðòèí T (Los1) — ÿâëÿåòñÿ åäèíñòâåííûì èç èçâåñòíûõ íà
ñåãîäíÿ òðàíñïîðòíûõ ôàêòîðîâ, ñïîñîáíûõ ñâÿçûâàòüñÿ
ñ ÐÍÊ áåç ïîñðåäíèêîâ (Arts et al., 1998). Ýòîò áåëîê îòâå÷àåò çà òðàíñïîðò òÐÍÊ. Îí ìîæåò îïîçíàâàòü òîëüêî
ñîçðåâøóþ òÐÍÊ è òåì ñàìûì îñóùåñòâëÿòü êîíòðîëü çà
ïðîöåññàìè åå ìîäèôèêàöèè è ñïëàéñèíãà (Kutay et al.,
1998; Lund, Dahlberg, 1998).
Ýêñïîðòíûé ôàêòîð Tap-1 (NXF1, ñîãëàñíî äðóãîé
íîìåíêëàòóðå), ãîìîëîãè÷íûé Mex67, — ôàêòîð, ýêñïîðòèðóþùèé ìÐÍÊ ó äðîææåé, îáåñïå÷èâàåò òðàíñïîðò ÐÍÊ ðåòðîâèðóñîâ, õîòÿ ñóùåñòâóåò ïðåäïîëîæåíèå î òîì, ÷òî ýòîò ôàêòîð ìîæåò îáåñïå÷èâàòü ýêñïîðò
ýíäîãåííîé ìÐÍÊ ó ìëåêîïèòàþùèõ (Gruter et al., 1998;
Katahira et al., 1999). Óñòàíîâëåíî, ÷òî ó äðîææåé â ýêñïîðòå ìÐÍÊ êðîìå Mex67 ó÷àñòâóþò äðóãèå ôàêòîðû,
òàêèå êàê Np13, Nab2, Hrp1 è Dbp5 (Cole, 2000). Áåëêè
Np13, Nab2 è Hrp1 ñâÿçûâàþòñÿ ñ ìÐÍÊ â ÿäðå è ñ íóêëåîïîðèíàìè Gle1 è Gle2, à áåëîê Dbp5 ó÷àñòâóåò â äåêîìïàêòèçàöèè ÐÍÊ íà öèòîïëàçìàòè÷åñêîé ñòîðîíå ÿäåðíîé ïîðû (Macara, 2001).
Èññëåäîâàíèÿ ýêñïîðòà 50-íàíîìåòðîâîé ÐÍÏ-÷àñòèöû — ïðîäóêòà ãåíîâ êîëåö Áàëüáèàíè â ñëþííûõ æåëåçàõ õèðîíîìóñà, âûïîëíåííûå ñ ïîìîùüþ ñêàíèðóþùåãî ýëåêòðîííîãî ìèêðîñêîïà, ïîçâîëèëè âûÿâèòü ïîñëåäîâàòåëüíûå ýòàïû ðåîðãàíèçàöèè ßÏÊ â òå÷åíèå
ýòîãî ïðîöåññà (Kiseleva et al., 1996, 1998). Áûëî ïîêàçàíî,
÷òî â íåàêòèâíîì ñîñòîÿíèè îáà âõîäà â öåíòðàëüíûé êàíàë ïîðû çàêðûòû ïåðèôåðè÷åñêèìè ãðàíóëàìè òðàíñïîðòåðà, à ñî ñòîðîíû ÿäðà — äîïîëíèòåëüíî ôèáðèëëàìè áàñêåò-ñòðóêòóðû. Íà ïåðâîì ýòàïå ýêñïîðòà ÐÍÏ-÷àñòèöà ïðèêðåïëÿåòñÿ ê âåðõóøêå áàñêåò-ñòðóêòóðû, ôèáðèëëû êîòîðîé ôîðìèðóþò óâåëè÷èâàþùååñÿ â ðàçìåðå
òåðìèíàëüíîå êîëüöî. Ïðåäïîëàãàåòñÿ, ÷òî Nup153 è
Nup98 ïðèíèìàþò àêòèâíîå ó÷àñòèå â ýòîì ñîáûòèè (Allen et al., 2000; Ryan, Wente, 2000). ×àñòèöà ïîñòåïåííî
ïðîäâèãàåòñÿ âíóòðü áàñêåòà, ãäå îíà äåêîìïàêòèçóåòñÿ
â 26-íàíîìåòðîâóþ ôèáðèëëó è ïîâîðà÷èâàåòñÿ, îðèåíòèðóÿñü òàê, ÷òîáû ïåðâûì â öåíòðàëüíûé êàíàë ïîðû
ïðîíèê 5S-êîíåö (Kiseleva et al., 1996; Daneholt, 1997). Íà
ñëåäóþùåì ýòàïå â ïåðèôåðè÷åñêîé ãðàíóëå òðàíñïîðòåðà ñî ñòîðîíû ÿäðà îòêðûâàåòñÿ îòâåðñòèå è ÐÍÏ-ôèáðèëëà íà÷èíàåò ïåðåìåùàòüñÿ âíóòðü ïîðû (Kiseleva et
al., 1996, 1998). Âíóòðåííèé äèàìåòð êàíàëà òðàíñïîðòåðà, èìåâøèé äî ýòîãî ðàçìåð 10 íì, ðàñøèðÿåòñÿ äî
894
Í. Â. Ãóáàíîâà, Ê. Í. Ìîðîçîâà, Å. Â. Êèñåëåâà
26 íì, è ôèáðèëëà ïåðåìåùàåòñÿ â ñòîðîíó öèòîïëàçìû.
 ïåðèôåðè÷åñêîé ãðàíóëå ßÏÊ ñî ñòîðîíû öèòîïëàçìû
òàêæå ôîðìèðóåòñÿ îòâåðñòèå äèàìåòðîì 26 íì, è
ÐÍÏ-ôèáðèëëà ïîëíîñòüþ âûõîäèò â öèòîïëàçìó, ãäå
íà÷èíàåòñÿ ïðîöåññ òðàíñëÿöèè. Ïîñëå îêîí÷àíèÿ òðàíñïîðòà âñå êîìïîíåíòû ßÏÊ âîçâðàùàþòñÿ â èñõîäíîå
ñîñòîÿíèå. Áûëî óñòàíîâëåíî, ÷òî â ïðîöåññå òðàíñïîðòà
ïåðèôåðè÷åñêèå ãðàíóëû òðàíñïîðòåðà ìîãóò ñìåùàòüñÿ
â âåðòèêàëüíîì íàïðàâëåíèè íà 5 íì, à ñàìà ïîðà —
óïëîùàòüñÿ èëè âûòÿãèâàòüñÿ, ÷òî, âîçìîæíî, ñïîñîáñòâóåò áîëåå ýôôåêòèâíîìó äâèæåíèþ òðàíñïîðòèðóåìîé
ìîëåêóëû. Ïîñêîëüêó ßÏÊ ñ îäíîé ñòîðîíû òåñíî ñâÿçàí
ñ ëàìèíîé (Goldberg et al., 1998) è, âîçìîæíî, ñ ÿäåðíûì
ìàòðèêñîì (Kiseleva et al., 2004á), à ñ äðóãîé, ÷åðåç ÿäåðíóþ îáîëî÷êó, — ñ öèòîñêåëåòîì, ìîæíî ïðåäïîëîæèòü,
÷òî â ðåãóëÿöèè ïðîöåññà ÿäåðíî-öèòîïëàçìàòè÷åñêîãî
òðàíñïîðòà ìîëåêóë ýòè âíóòðèêëåòî÷íûå êîìïîíåíòû
òàêæå ïðèíèìàþò àêòèâíîå ó÷àñòèå.
Ì î ä å ë è ò ð à í ñ ï î ð ò à ì î ë å ê ó ë. Â íàñòîÿùåå
âðåìÿ ïðåäëîæåíû òðè ìîäåëè òðàíñïîðòà ÷åðåç ßÏÊ.
Ñîãëàñíî ïåðâîé ìîäåëè, òðàíñïîðò ìîëåêóë ïî öåíòðàëüíîìó êàíàëó ßÏÊ îáóñëîâëåí ïðèñóòñòâèåì â íóêëåîïîðèíàõ FG-ïîâòîðîâ, êîòîðûå èìåþò ñðîäñòâî ê
ôàêòîðàì, ó÷àñòâóþùèì â ðåãóëÿöèè òðàíñïîðòà (Ribbeck, Görlich, 2002; Strawn et al., 2004). Èññëåäîâàíèå
ñòðóêòóðû èìïîðòèíà â, TAP è NTF2 ïîêàçàëè, ÷òî âñå
òðè ìîëåêóëû ñîäåðæàò êëàñòåðû ãèäðîôîáíûõ àìèíîêèñëîò, êîòîðûå ñïîñîáíû âçàèìîäåéñòâîâàòü ñ FG-ïîâòîðàìè íóêëåîïîðèíîâ. Ñîãëàñíî ïðåäëîæåííîé ìîäåëè, FG-ïîâòîðû íóêëåîïîðèíîâ öåíòðàëüíîãî êàíàëà
ôîðìèðóþò ñâîåîáðàçíîå ãèäðîôîáíîå ñèòî, êîòîðîå
äàåò âîçìîæíîñòü ïàññèâíî äèôôóíäèðîâàòü òîëüêî ìåëêèì ìîëåêóëàì. Ïðè òðàíñïîðòèðîâêå êðóïíûõ ìîëåêóë
ãèäðîôîáíûå ó÷àñòêè òðàíñïîðòíûõ ôàêòîðîâ âçàèìîäåéñòâóþò ñ ãèäðîôîáíûì ñèòîì è ëîêàëüíî ðàñòâîðÿþò
ïðåãðàäó, ÷òî ïîçâîëÿåò èì ïðîäâèãàòüñÿ ïî öåíòðàëüíîìó êàíàëó. Ïîñëå ïðîõîæäåíèÿ òðàíñïîðòíîãî ôàêòîðà â
êîìïëåêñå ñ ïåðåíîñèìîé ìîëåêóëîé ãèäðîôîáíàÿ ñåòü
âîññòàíàâëèâàåòñÿ.
Âòîðàÿ ìîäåëü ïåðåíîñà ìîëåêóë ÷åðåç ÿäåðíóþ
ïîðó îñíîâàíà íà ñóùåñòâîâàíèè ðàçëè÷íîãî ñðîäñòâà
òðàíñïîðòíûõ ðåöåïòîðîâ ê FG-ïîâòîðàì íóêëåîïîðèíîâ. Áûëî îáíàðóæåíî, ÷òî â ïðîöåññå ýêñïîðòà èç ÿäðà
ïî íàïðàâëåíèþ ê äèñòàëüíî ðàñïîëîæåííûì íóêëåîïîðèíàì ñðîäñòâî FG-ïîâòîðîâ ê òðàíñïîðòíîìó ôàêòîðó
âîçðàñòàåò â 20 ðàç, òàê ÷òî òðàíñïîðòèðóåìàÿ ìîëåêóëà
ìîæåò ïåðåäàâàòüñÿ îò îäíîãî íóêëåîïîðèíà ê äðóãîìó,
êàê ýñòàôåòíàÿ ïàëî÷êà (Ben-Efraim, Gerace, 2001). Îäíàêî ýòà ìîäåëü â íàñòîÿùåå âðåìÿ ïîäâåðãàåòñÿ êðèòèêå, òàê êàê îíà íå îáåñïå÷èâàåò âûÿâëåííîé âûñîêîé
ñêîðîñòè òðàíñïîðòà ìîëåêóë (áîëåå 300 ìîëåêóë â 1 ñ)
÷åðåç ßÏÊ â îáîèõ íàïðàâëåíèÿõ (Ribbeck, Görlich, 2001;
Siebrasse, Peters, 2002).
Ðàóò ñ êîëëåãàìè (Rout et al., 2000) ïðåäëîæèëè òðåòüþ
ìîäåëü, ñîãëàñíî êîòîðîé ìîëåêóëû äèôôóíäèðóþò ÷åðåç öåíòðàëüíûé êàíàë ßÏÊ, à íàïðàâëåíèå èõ òðàíñïîðòà îïðåäåëÿåòñÿ ëîêàëèçàöèåé ñâÿçûâàþùèõñÿ ñ íèìè
òðàíñïîðòíûõ ôàêòîðîâ, èìåþùèõ ñðîäñòâî ê íóêëåîïîðèíàì öèòîïëàçìàòè÷åñêîãî èëè âíóòðèÿäåðíîãî îòäåëà
ïîðû. Äåéñòâèòåëüíî, ýëåêòðîííî-ìèêðîñêîïè÷åñêèå èññëåäîâàíèÿ ïîêàçàëè, ÷òî òðàíñïîðòíûå ôàêòîðû ìîãóò
íàêàïëèâàòüñÿ íà öèòîïëàçìàòè÷åñêèõ ôèëàìåíòàõ, è
ýòî, êàê ïðåäïîëàãàëîñü, ïðåäøåñòâóåò èìïîðòó (Paschal,
2002). Îäíàêî áîëåå ïîçäíèå èññëåäîâàíèÿ ïîêàçàëè, ÷òî
ó÷àñòèå öèòîïëàçìàòè÷åñêèõ ôèëàìåíòîâ íå ÿâëÿåòñÿ
îáÿçàòåëüíûì ôàêòîðîì äëÿ îáåñïå÷åíèÿ òðàíñïîðòà ìîëåêóë (Walther et al., 2002), è ýòî äåëàåò òðåòüþ ìîäåëü
ñîìíèòåëüíîé. Êðîìå òîãî, ýòà ìîäåëü íå îáúÿñíÿåò, ïî÷åìó ïðè òðàíñïîðòå ÷åðåç ïîðó êðóïíûõ ÐÍÏ-÷àñòèö
ðåãèñòðèðóþòñÿ ñòðóêòóðíûå èçìåíåíèÿ â öåíòðàëüíîì
êàíàëå ïîðû.
Îñîáåííîñòè ñáîðêè ÿäåðíûõ ïîð
in vitro è in vivo
Ïðîöåññ äåëåíèÿ ÿäåð â êëåòêàõ âûñøèõ ýóêàðèîò
ïðîèñõîäèò ïî òèïó îòêðûòîãî ìèòîçà. Íà ñòàäèè ïðîôàçû ìèòîçà õðîìîñîìû êîíäåíñèðóþòñÿ è ÿäåðíàÿ îáîëî÷êà âìåñòå ñ ëàìèíîé ïîëíîñòüþ èëè ÷àñòè÷íî (äëÿ
äðîçîôèëû) ðàçáèðàåòñÿ, à íà ñòàäèè òåëîôàçû âñå ñîáèðàåòñÿ âíîâü. Ñáîðêà è ðàçáîðêà ÿäåðíûõ ïîð èíòåíñèâíî èçó÷àëèñü è èçó÷àþòñÿ â ýêñïåðèìåíòàõ in vitro, áëàãîäàðÿ êîòîðûì áûëà ïîëó÷åíà óíèêàëüíàÿ èíôîðìàöèÿ
î ïîñëåäîâàòåëüíûõ ýòàïàõ è ìåõàíèçìàõ ðåãóëÿöèè
ýòèõ ïðîöåññîâ. Ïðè ýòîì â áîëüøèíñòâå ñëó÷àåâ èñïîëüçóåòñÿ öèòîïëàçìàòè÷åñêèé ýêñòðàêò èç îîöèòîâ àìôèáèé, êîòîðûé èíêóáèðóåòñÿ ñ êîìïàêòíûì õðîìàòèíîì ñïåðìû, è çà 1.5—2.5 ÷ òàêîé èíêóáàöèè ôîðìèðóþòñÿ ôóíêöèîíàëüíî àêòèâíûå (ñïîñîáíûå ê ðåïëèêàöèè
è òðàíñêðèïöèè) ÿäðà ñî çðåëûìè ÿäåðíûìè ïîðàìè
(Marshall et al., 1997; Lohka, 1998). Íà ïåðâîì ýòàïå ñáîðêè ãëàäêèå è øåðîõîâàòûå ïóçûðüêè ýíäîïëàçìàòè÷åñêîãî ðåòèêóëóìà, ðàçëè÷àþùèåñÿ ïî ñîñòàâó áåëêîâ, ñâÿçûâàþòñÿ ñ ïîâåðõíîñòüþ äåêîíäåíñèðóþùåãîñÿ õðîìàòèíà, à çàòåì ñëèâàþòñÿ âìåñòå, ôîðìèðóÿ âíóòðåííþþ
è íàðóæíóþ ÿäåðíûå ìåìáðàíû (Marshall, 1997). Óñòàíîâëåíî, ÷òî äëÿ îñóùåñòâëåíèÿ ýòîãî ïðîöåññà íåîáõîäèìû èîíû Ca2+ (Peters, Mayer, 1998) è Ran-ÃÒÔ (Clarke,
Zhang, 2001). Ïîêàçàíî òàêæå, ÷òî èìïîðòèí â ìîæåò èíãèáèðîâàòü ñëèÿíèå ïóçûðüêîâ è ñáîðêó ßÏÊ (Harel et
al., 2003).
Èññëåäîâàíèÿ ôîðìèðóþùåéñÿ in vitro ÿäåðíîé îáîëî÷êè ñ èñïîëüçîâàíèåì âûñîêîðàçðåøàþùåé ñêàíèðóþùåé ýëåêòðîííîé ìèêðîñêîïèè ïîçâîëèëè ïîëó÷èòü íîâûå äàííûå î ïîñëåäîâàòåëüíîñòè ñîáûòèé, ïðîèñõîäÿùèõ â îáëàñòè öèòîïëàçìàòè÷åñêîãî êîìïàðòìåíòà
ÿäåðíîé ïîðû (Goldberg et al., 1997; Marshall, 1997).
Áûëî ïîêàçàíî, ÷òî ïîñëå ôîðìèðîâàíèÿ âîêðóã äåêîìïàêòèçóþùåãîñÿ õðîìàòèíà êðóïíûõ ôðàãìåíòîâ ÿäåðíîé îáîëî÷êè â íèõ íà÷èíàåòñÿ ñáîðêà ßÏÊ. Ñíà÷àëà â
ðàçëè÷íûõ ó÷àñòêàõ íàðóæíîé ÿäåðíîé ìåìáðàíû ïîÿâëÿþòñÿ íåáîëüøèå óãëóáëåíèÿ, êîòîðûå çàòåì ïðåâðàùàþòñÿ â íåáîëüøèå ïîðû ðàçìåðîì 10—20 íì. Äàëåå äèàìåòð ïîð óâåëè÷èâàåòñÿ äî 40 íì è íà÷èíàåòñÿ ïîñëåäîâàòåëüíîå ôîðìèðîâàíèå ñíà÷àëà öåíòðàëüíûõ, à çàòåì
ïåðèôåðè÷åñêèõ êîìïîíåíòîâ ßÏÊ. Óñòàíîâëåíî, ÷òî
ñáîðêà ñîñòàâëÿþùèõ ïîðó îòäåëüíûõ êîìïîíåíòîâ ïðîèñõîäèò àñèíõðîííî: ñíà÷àëà îáðàçóåòñÿ îäíà ñîñòàâëÿþùàÿ êîìïîíåíò ñóáúåäèíèöà, çàòåì âòîðàÿ è ò. ä. Ïðè
ýòîì ïîðà ïîñòåïåííî óâåëè÷èâàåòñÿ â ðàçìåðå è çà
4—6 ìèí ïðåâðàùàåòñÿ â çðåëóþ ïîðó äèàìåòðîì 110—
120 íì (Goldberg et al., 1997). Ýòè äàííûå âïåðâûå ïðîäåìîíñòðèðîâàëè, ÷òî ñáîðêà ßÏÊ îñóùåñòâëÿåòñÿ çà
ñ÷åò ôîðìèðîâàíèÿ ïðîìåæóòî÷íûõ ñòðóêòóð. Ñëåäóåò îòìåòèòü, ÷òî ïðîöåññ ñáîðêè ÿäåðíûõ ïîð ñî ñòîðîíû ÿäðà äî ñèõ ïîð äî êîíöà íå èçó÷åí, òàêæå íåÿñåí è
âîïðîñ î ñèíõðîííîñòè ôîðìèðîâàíèÿ ïåðèôåðè÷åñêèõ
îòäåëîâ ÿäåðíûõ ïîð. Ñ èñïîëüçîâàíèåì ìèòîòè÷åñêîãî
Ñòðóêòóðíàÿ îðãàíèçàöèÿ, ôóíêöèÿ è äèíàìèêà ÿäåðíûõ ïîð
ýêñòðàêòà â îïûòàõ in vitro áûëî ïîêàçàíî, ÷òî ðàñïàä
ÿäåðíîé îáîëî÷êè ïðîèñõîäèò çà ñ÷åò ôîðìèðîâàíèÿ
äëèííûõ òðóáî÷åê è öèñòåðí, íàïîìèíàþùèõ êîìïîíåíòû ýíäîïëàçìàòè÷åñêîãî ðåòèêóëóìà (Cotter et al.,
1998).
Ðåçóëüòàòû ýêñïåðèìåíòîâ ïî èññëåäîâàíèþ ìåõàíèçìîâ ðàñïàäà è ñáîðêè ÿäåðíûõ ïîð in vitro áûëè ïîäòâåðæäåíû íàìè â îïûòàõ in vivo ïðè èçó÷åíèè äåëåíèÿ
ÿäåð â ðàííèõ ýìáðèîíàõ äðîçîôèëû (Kiseleva et al.,
2001). Áûëî ïðîäåìîíñòðèðîâàíî, ÷òî ïðè ðàçáîðêå
ßÏÊ, êîòîðàÿ íà÷èíàåòñÿ â ïðîôàçå ìèòîçà, ñíà÷àëà ðàçáèðàþòñÿ öåíòðàëüíûå, çàòåì ïåðèôåðè÷åñêèå êîìïîíåíòû ïîð, ïîñëå ÷åãî ðàñïàäàåòñÿ ÿäåðíàÿ îáîëî÷êà.
Ñáîðêà íîâûõ ïîð íà÷èíàåòñÿ íà ñòàäèè ðàííåé òåëîôàçû, ïîñëå ôîðìèðîâàíèÿ ÿäåðíîé îáîëî÷êè, è ïðîõîäèò
÷åðåç òå æå ïðîìåæóòî÷íûå ñòðóêòóðû (ðèñ. 4), êîòîðûå
íàáëþäàëèñü ïðè ôîðìèðîâàíèè ßÏÊ â îïûòàõ in vitro.
Èíòåðåñíî, ÷òî ôîðìèðîâàíèå ïîð â ýêñïåðèìåíòàõ in
vivo èíèöèèðóåòñÿ ïðåèìóùåñòâåííî â ó÷àñòêàõ ñëèÿíèÿ
ìåìáðàí ïóçûðüêîâ ýíäîïëàçìàòè÷åñêîãî ðåòèêóëóìà ñ
íàðóæíîé ÿäåðíîé ìåìáðàíîé. Ïðè ýòîì ñíà÷àëà âñòðàèâàåòñÿ öåíòðàëüíûé òðàíñïîðòåð, çàòåì ñîáèðàþòñÿ çâåçä÷àòîå è òîíêîå êîëüöà è â ïîñëåäíþþ î÷åðåäü ôîðìèðóþòñÿ öèòîïëàçìàòè÷åñêèå ãðàíóëû è ôèáðèëëû (Kiseleva et al., 2001). Òàêèì îáðàçîì, ýòîò ïðîöåññ ÿâëÿåòñÿ
çåðêàëüíûì îòðàæåíèåì ðàçáîðêè ßÏÊ â ïðîôàçå. Ìîæíî ïðåäïîëîæèòü, ÷òî ñáîðêà ßÏÊ ñî ñòîðîíû íóêëåîïëàçìû äîëæíà ïðîèñõîäèòü àíàëîãè÷íî òîìó, ÷òî íàáëþäàåòñÿ ñî ñòîðîíû öèòîïëàçìû, çà èñêëþ÷åíèåì
òîãî, ÷òî âìåñòî ãðàíóë ñ ôèáðèëëàìè áóäåò ôîðìèðîâàòüñÿ áàñêåò-ñòðóêòóðà.
Ñóùåñòâóþò íåîäíîçíà÷íûå äàííûå îòíîñèòåëüíî
ïîñëåäîâàòåëüíîñòè ñáîðêè íóêëåîïîðèíîâ â ßÏÊ â ðàííåé àíàôàçå. Ýêñïåðèìåíòû in vivo ïîêàçàëè, ÷òî â ïîçäíåé àíàôàçå ñ õðîìàòèíîì ñâÿçûâàþòñÿ íóêëåîïîðèí
Nup153 è áåëîê ÿäåðíîé ëàìèíû LAP2 (Bodoor et al.,
1999a, 1999b). Ïîñëå îáðàçîâàíèÿ äâóõ ìåìáðàí ÿäåðíîé
îáîëî÷êè âîêðóã äåêîìïàêòèçóþùèõñÿ õðîìîñîì èíèöèèðóåòñÿ ôîðìèðîâàíèå ßÏÊ è âñòðàèâàíèå â íèõ áåëêà
Pom121 è ñóáêîìïëåêñà p62, âêëþ÷àþùåãî â ñåáÿ òàêæå
áåëêè p58, p 54 è p45. Çàòåì â ÿäåðíóþ ïîðó âñòðàèâàþòñÿ íóêëåîïîðèí CAN/Nup214, êîòîðûé îáðàçóåò êîìïëåêñ ñ áåëêîì Nup88(84), è áåëîê gp210, êîòîðûé àññîöèèðóåòñÿ ñ ìåìáðàíàìè ÿäåðíîé îáîëî÷êè â ïîçäíåé òåëîôàçå. Ýòè äàííûå ñîãëàñóþòñÿ ñ áîëåå ïîçäíèìè ýêñïåðèìåíòàìè, â êîòîðûõ ïðîâîäèëîñü ïðèæèçíåííîå èññëåäîâàíèå êóëüòóðû êëåòîê, ãäå áûëî ïîêàçàíî, ÷òî
Pom121 âïåðâûå íàáëþäàåòñÿ âîêðóã êîìïàêòíûõ õðîìîñîì â ïîçäíåé àíàôàçå (Imreh, 2000). Ïî äàííûì äðóãèõ àâòîðîâ (Smythe et al., 2000), ýêñïåðèìåíòû ïî ñáîðêå ßÏÊ èç ýêñòðàêòîâ ÿèö Xenopus ïîêàçàëè, ÷òî ñíà÷àëà
ñîáèðàåòñÿ êîìïëåêñ, ñîñòîÿùèé èç íóêëåîïîðèíîâ
Nup62 è Nup214, à çàòåì ê íåìó ïðèñîåäèíÿåòñÿ Nup153.
Ñóùåñòâóåò òàêæå ïðåäïîëîæåíèå î òîì, ÷òî ñáîðêà
ßÏÊ ó ïîçâîíî÷íûõ èíèöèèðóåòñÿ ïóòåì çàõâàòà õðîìàòèíîì êîìïëåêñà Nup107-Nup160 (Walther et al., 2003;
Harel et al., 2003b). Äî ñèõ ïîð íåÿñíî, êàêîâà ïîñëåäîâàòåëüíîñòü ñáîðêè áåëêîâ íà ñàìûõ íà÷àëüíûõ ýòàïàõ
ôîðìèðîâàíèÿ ßÏÊ de novo è ÷òî èíèöèèðóåò ñëèÿíèå
ìåìáðàí â ýòîì ó÷àñòêå. Ïðåäïîëàãàåòñÿ, ÷òî Pom121 íåîáõîäèì íà ïåðâîì ýòàïå ñëèÿíèÿ äâóõ ìåìáðàí ÿäåðíîé
îáîëî÷êè (Bodoor et al., 1999), òîãäà êàê gp210, â áîëüøîì êîëè÷åñòâå íàêàïëèâàþùèéñÿ âáëèçè ïîðû, îáåñïå÷èâàåò åå ñòàáèëüíîñòü è âñòðàèâàíèå â ýòîò ó÷àñòîê
äðóãèõ íóêëåîïîðèíîâ (Vasu, Forbes, 2001). Âîïðîñ î
895
ñáîðêå—ðàçáîðêå ßÏÊ ó íèçøèõ ýóêàðèîò, ó êîòîðûõ
äåëåíèå ÿäåð ïðîèñõîäèò ïî òèïó çàêðûòîãî ìèòîçà,
ïîêà äîñêîíàëüíî íå èçó÷åí. Ñîãëàñíî èìåþùèìñÿ äàííûì, ßÏÊ äðîææåé ðàçáèðàåòñÿ è ñîáèðàåòñÿ àñèíõðîííî, âîçìîæíî ÷åðåç ïðîìåæóòî÷íûå êîìïîíåíòû, àíàëîãè÷íûå òåì, ÷òî îïèñàíû äëÿ âûñøèõ ýóêàðèîò (Winey et
al., 1997; Kiseleva et al., 2004).
Íàøè ïîñëåäíèå èññëåäîâàíèÿ (Onischenko et al.,
2005) ïîêàçàëè, ÷òî âåäóùàÿ ðåãóëÿòîðíàÿ ðîëü â ðàçáîðêå è ñáîðêå ïîðîâûõ êîìïëåêñîâ ïðèíàäëåæèò öèêëèíçàâèñèìîé êèíàçå 1 (cdk1) è öèêëèíó B (cyclin B). Óâåëè÷åíèå êîíöåíòðàöèè öèêëèíà B äî ïîðîãîâîãî çíà÷åíèÿ àêòèâèðóåò öèêëèíçàâèñèìóþ êèíàçó cdk1, êîòîðàÿ
â ïðîôàçå ôîñôîðèëèðóåò íóêëåîïîðèíû è èíèöèèðóåò ðàñïàä ÿäåðíûõ ïîð. Ñáîðêà ÿäåðíîé îáîëî÷êè è
ßÏÊ íà÷èíàåòñÿ â òåëîôàçå, êîãäà, êàê áûëî ïîêàçàíî
äëÿ ýìáðèîíîâ äðîçîôèëû, ïîä äåéñòâèåì ôîñôàòàç PP1
è PP2A ïðîèñõîäèò äåôîñôîðèëèðîâàíèå íóêëåîïîðèíîâ.
Çàêëþ÷åíèå
Ïîäâîäÿ èòîã, ñëåäóåò ïîä÷åðêíóòü, ÷òî èìåííî êîìïëåêñíîå èñïîëüçîâàíèå öèòîëîãè÷åñêèõ, áèîõèìè÷åñêèõ è ìîëåêóëÿðíî-áèîëîãè÷åñêèõ ìåòîäîâ îáåñïå÷èëî
áûñòðûé ïðîãðåññ â èçó÷åíèè òîíêèõ äåòàëåé ñòðóêòóðíîé îðãàíèçàöèè è áåëêîâîãî ñîñòàâà ÿäåðíûõ ïîð. Ê íàñòîÿùåìó âðåìåíè ïðîäåìîíñòðèðîâàíà êîíñåðâàòèâíîñòü ñòðîåíèÿ ßÏÊ â ýâîëþöèè è ïîêàçàíî, ÷òî êàæäàÿ
ïîðà ñîñòîèò èç òðåõ ñâÿçàííûõ ìåæäó ñîáîé êîìïàðòìåíòîâ è áîëüøîãî êîëè÷åñòâà èíäèâèäóàëüíûõ êîìïîíåíòîâ. Ïîêàçàíî, ÷òî áåëêîâ ïîðû îêîëî 30 è îíè ìîãóò
ôîðìèðîâàòü ñëîæíûå êîìïëåêñû, ó÷àñòâóþùèå â îðãàíèçàöèè èíäèâèäóàëüíûõ êîìïîíåíòîâ ïîð. Èññëåäîâàíû ìåõàíèçìû èìïîðòà è ýêñïîðòà ìîëåêóë ÷åðåç
ÿäåðíûå ïîðû è ïðåäëîæåíî íåñêîëüêî ìîäåëåé ýòîãî
ïðîöåññà. Êîìïëåêñíûé ïîõîä â èçó÷åíèè ñáîðêè è ðàçáîðêè ßÏÊ â óñëîâèÿõ in vivo è in vitro ïîçâîëèë âûÿñíèòü ïîñëåäîâàòåëüíîñòü ðàñïàäà è ñáîðêè èõ èíäèâèäóàëüíûõ êîìïîíåíòîâ íà ðàçíûõ ñòàäèÿõ ìèòîçà, à òàêæå
îïðåäåëèòü âðåìåíí*óþ äèíàìèêó âñòðàèâàíèÿ íóêëåîïîðèíîâ â ôîðìèðóþùóþñÿ ïîðó.
 òî æå âðåìÿ ìíîãèå âîïðîñû, ñâÿçàííûå ñî ñòðóêòóðîé, äèíàìèêîé è ôóíêöèåé ßÏÊ, âñå åùå íå äî êîíöà
èññëåäîâàíû. Òàê, íàïðèìåð, äî ñèõ ïîð ÷åòêî íå óñòàíîâëåíî, êàêèå íóêëåîïîðèíû âõîäÿò â ñîñòàâ ôèëàìåíòîâ áàñêåò-ñòðóêòóðû ßÏÊ, êàê ðàñïîëàãàþòñÿ ðàçëè÷íûå äîìåíû êàæäîãî íóêëåîïîðèíà âíóòðè ïîðû, êàêîâà
ñòðóêòóðà öåíòðàëüíîãî êàíàëà ßÏÊ, êàêóþ ðîëü â
òðàíñïîðòå ìîëåêóë âûïîëíÿþò ðàçëè÷íûå ïîâòîðû,
ïðèñóòñòâóþùèå â íóêëåîïîðèíàõ, êàêèì îáðàçîì èíòåãðàëüíûå áåëêè ßÏÊ ðàñïðåäåëÿþòñÿ ñðåäè êîìïàðòìåíòîâ ßÏÊ ïðè ðàçáîðêå ÿäåðíûõ ïîð, êàê ïðîèñõîäèò
ñáîðêà ßÏÊ â èíòåðôàçå è â ðàñòóùèõ íåäåëÿùèõñÿ ÿäðàõ, êàêèì îáðàçîì ýëåìåíòû öèòîñêåëåòà è ÿäåðíîãî
ìàòðèêñà âîâëå÷åíû â ðåãóëÿöèþ òðàíñïîðòà ÷åðåç ÿäåðíóþ ïîðó è ò. ä. Äåòàëüíîå èññëåäîâàíèå ýòèõ âîïðîñîâ
îáåñïå÷èò ïîëó÷åíèå íîâûõ äàííûõ, êîòîðûå ïîçâîëÿò
ëó÷øå ïîíÿòü êàê ñòðóêòóðíóþ è ôóíêöèîíàëüíóþ äèíàìèêó ßÏÊ â ðàçíûõ êëåòêàõ, òàê è ðåãóëÿòîðíûå ìåõàíèçìû ÿäåðíî-öèòîïëàçìàòè÷åñêîãî òðàíñïîðòà.
Àâòîðû âûðàæàþò áëàãîäàðíîñòü È. Ê. Çàõàðîâó çà
êðèòè÷åñêóþ îöåíêó ðóêîïèñè è öåííûå çàìå÷àíèÿ.
896
Í. Â. Ãóáàíîâà, Ê. Í. Ìîðîçîâà, Å. Â. Êèñåëåâà
Ðèñ. 4. Ôîòîãðàôèè ïðîìåæóòî÷íûõ ñòðóêòóð öèòîïëàçìàòè÷åñêîãî êîìïàðòìåíòà, ôîðìèðóþùèõñÿ ïðè ñáîðêå ÿäåðíûõ ïîð â
ðàííèõ ýìáðèîíàõ äðîçîôèëû (à—å), è ñõåìà ïîñëåäîâàòåëüíûõ ýòàïîâ ýòîãî ïðîöåññà (Kiseleva et al., 2001).
Ñòðóêòóðíàÿ îðãàíèçàöèÿ, ôóíêöèÿ è äèíàìèêà ÿäåðíûõ ïîð
Ðàáîòà âûïîëíåíà ïðè ôèíàíñîâîé ïîääåðæêå Ðîññèéñêîãî ôîíäà ôóíäàìåíòàëüíûõ èññëåäîâàíèé (ïðîåêò
04-48261-à), ôîíäà Wellcome Trust (Àíãëèÿ), à òàêæå
ãðàíòà äëÿ ìîëîäûõ ó÷åíûõ èì. àêàä. Ëàâðåíòüåâà ÑÎ
ÐÀÍ (ïðîåêò 106).
Ñïèñîê ëèòåðàòóðû
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Ïîñòóïèëà 21 III 2006
STRUCTURAL ORGANIZATION, FUNCTIONS AND DYNAMICS OF NUCLEAR PORES
N. V. Gubanova,1 K. N. Morozova, E. V. Kiseleva2
Institute of Cytology and Genetics, Siberian Branch of the RAS, Novosibirsk;
e-mail: 1 [email protected]; 2 [email protected]
This review summarized data on the morphological and biochemical analysis of nuclear pore complexes,
which are complex organelles providing the route of passive and active nuclear-cytoplasmic transport to different molecules in the eukaryotic cell. The morphology and functional role of nuclear pores in higher and lower
eukaryotes, and molecular aspects of the import and export of molecules from the nucleus are described in addition to factors involved in the regulation of these process. Special attention has been paid to sequential steps of
the nuclear pore assembly in vitro and in vivo.
K e y w o r d s: nuclear pores, nuclear-cytoplasmic transport, nuclear pore dynamic, mitosis.
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