Matlack K E, Plath K, Misselwitz B, Rapoport T A
Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
Science. 1997 Aug 15;277(5328):938-41. doi: 10.1126/science.277.5328.938.
Posttranslational protein translocation across the endoplasmic reticulum membrane of yeast requires a seven-component transmembrane complex (the Sec complex) in collaboration with the lumenal Kar2 protein (Kar2p). A translocation substrate was initially bound to the cytosolic face of the purified Sec complex in a signal-sequence-dependent but Kar2p- and nucleotide-independent manner. In a subsequent reaction, in which Kar2p interacted with the lumenal face of the Sec complex and hydrolyzed adenosine triphosphate, the substrate moved through a channel formed by the Sec complex and was released at the lumenal end. Movement through the channel occurred in detergent solution in the absence of a lipid bilayer.
酵母蛋白质在内质网膜上的翻译后易位需要一个由七个组分组成的跨膜复合物（Sec复合物）与腔内的Kar2蛋白（Kar2p）协同作用。易位底物最初以信号序列依赖性但不依赖Kar2p和核苷酸的方式结合到纯化的Sec复合物的胞质面。在随后的反应中，Kar2p与Sec复合物的腔内面相互作用并水解三磷酸腺苷，底物通过Sec复合物形成的通道移动并在腔端释放。在没有脂质双层的去污剂溶液中，底物通过通道移动。
