4w24

Publication Abstract from PubMed

Cotranslational protein translocation is a universally conserved process for secretory and membrane protein biosynthesis. Nascent polypeptides emerging from a translating ribosome are either transported across or inserted into the membrane via the ribosome-bound Sec61 channel. Here, we report structures of a mammalian ribosome-Sec61 complex in both idle and translating states, determined to 3.4 and 3.9 A resolution. The data sets permit building of a near-complete atomic model of the mammalian ribosome, visualization of A/P and P/E hybrid-state tRNAs, and analysis of a nascent polypeptide in the exit tunnel. Unprecedented chemical detail is observed for both the ribosome-Sec61 interaction and the conformational state of Sec61 upon ribosome binding. Comparison of the maps from idle and translating complexes suggests how conformational changes to the Sec61 channel could facilitate translocation of a secreted polypeptide. The high-resolution structure of the mammalian ribosome-Sec61 complex provides a valuable reference for future functional and structural studies.

Structure of the Mammalian ribosome-sec61 complex to 3.4 a resolution.,Voorhees RM, Fernandez IS, Scheres SH, Hegde RS Cell. 2014 Jun 19;157(7):1632-43. doi: 10.1016/j.cell.2014.05.024. Epub 2014 Jun , 12. PMID:24930395^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.