Cotranslational protein integration into the ER membrane is mediated by the binding of nascent chains to translocon proteins
Cotranslational protein integration into the ER membrane is mediated by the binding of nascent chains to translocon proteins
复制标题
DOI：
10.1016/s1097-2765(03)00304-6
复制
发表时间：
2003-08-01
期刊：
影响因子：
16
通讯作者：
Johnson, AE
中科院分区：
文献类型：
--
作者：
McCormick, PJ;Miao, YW;Johnson, AE
在共翻译蛋白质整合到内质网膜的过程中，每个跨膜(TM)片段通过转运子横向移动，到达脂质双层。光交联研究表明，每个新生的链TMα螺旋和信号锚序列的一个特定表面总是面对易位子中的Sec61α。这种非随机和TM序列依赖的定位表明，每个TM片段都与Sec61pha进行特定的接触，并保留在易位子内的一个固定位置，这一观察结果可以用每个TM序列与一个易位子蛋白的结合来最好地解释(S)。由于TM序列的疏水性与其从转位子中释放的速率无关，因此通过转位子的初生链的运动似乎主要是通过蛋白质-蛋白质相互作用而不是疏水的初生链-磷脂相互作用来调节的。
During cotranslational protein integration into the ER membrane, each transmembrane (TM) segment moves laterally through the translocon to reach the lipid bilayer. Photocrosslinking studies reveal that a particular surface of each nascent chain TM alpha helix and signal-anchor sequence always faces Sec61alpha in the translocon. This nonrandom and TM sequence-dependent positioning reveals that each TM segment makes specific contacts with Sec61alpha and is retained at a fixed location within the translocon, observations that are best explained by the binding of each TM sequence to a translocon protein(s). Since TM sequence hydrophobicity does not correlate with its rate of release from the translocon, nascent chain movement through the translocon appears to be mediated primarily by protein-protein interactions rather than hydrophobic nascent chain-phospholipid interactions.