Beckmann R, Bubeck D, Grassucci R, Penczek P, Verschoor A, Blobel G, Frank J
Howard Hughes Medical Institute, Laboratory of Cell Biology, Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
Science. 1997 Dec 19;278(5346):2123-6. doi: 10.1126/science.278.5346.2123.
An oligomer of the Sec61 trimeric complex is thought to form the protein-conducting channel for protein transport across the endoplasmic reticulum. A purified yeast Sec61 complex bound to monomeric yeast ribosomes as an oligomer in a saturable fashion. Cryo-electron microscopy of the ribosome-Sec61 complex and a three-dimensional reconstruction showed that the Sec61 oligomer is attached to the large ribosomal subunit by a single connection. Moreover, a funnel-shaped pore in the Sec61 oligomer aligned with the exit of a tunnel traversing the large ribosomal subunit, strongly suggesting that both structures function together in the translocation of proteins across the endoplasmic reticulum membrane.
Sec61三聚体复合物的寡聚体被认为形成了蛋白质转运通道，用于蛋白质穿过内质网的转运。纯化的酵母Sec61复合物以可饱和的方式作为寡聚体与单体酵母核糖体结合。核糖体-Sec61复合物的冷冻电子显微镜观察和三维重建表明，Sec61寡聚体通过单一连接附着于大核糖体亚基。此外，Sec61寡聚体中的漏斗形孔与穿过大核糖体亚基的通道出口对齐，强烈表明这两种结构在蛋白质跨内质网膜转运中共同发挥作用。
