5abb

Visualization of a polytopic membrane protein during SecY-mediated membrane insertionVisualization of a polytopic membrane protein during SecY-mediated membrane insertion

5abb, resolution 8.00Å Show:Asymmetric Unit Biological Assembly Structural highlights 5abb is a 3 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Experimental data: Check Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [B7MCR5_ECO45] The central subunit of the protein translocation channel SecYEG. Consists of two halves formed by TMs 1-5 and 6-10. These two domains form a lateral gate at the front which open onto the bilayer between TMs 2 and 7, and are clamped together by SecE at the back. The channel is closed by both a pore ring composed of hydrophobic SecY resides and a short helix (helix 2A) on the extracellular side of the membrane which forms a plug. The plug probably moves laterally to allow the channel to open. The ring and the pore may move independently.[HAMAP-Rule:MF_01465][RuleBase:RU000537] [PRRG_PRB01] Light-driven proton pump that generates photothrophic energy. [B7MIW7_ECO45] Essential subunit of the Sec protein translocation channel SecYEG. Clamps together the 2 halves of SecY. May contact the channel plug during translocation.[HAMAP-Rule:MF_00422] Publication Abstract from PubMed The biogenesis of polytopic membrane proteins occurs co-translationally on ribosomes that are tightly bound to a membrane-embedded protein-conducting channel: the Sec-complex. The path that is followed by nascent proteins inside the ribosome and the Sec-complex is relatively well established; however, it is not clear what the fate of the N-terminal transmembrane domains (TMDs) of polytopic membrane proteins is when the C-terminal TMDs domains are not yet synthesized. Here, we present the sub-nanometer cryo-electron microscopy structure of an in vivo generated ribosome-SecY complex that carries a membrane insertion intermediate of proteorhodopsin (PR). The structure reveals a pre-opened Sec-complex and the first two TMDs of PR already outside the SecY complex directly in front of its proposed lateral gate. Thus, our structure is in agreement with positioning of N-terminal TMDs at the periphery of SecY, and in addition, it provides clues for the molecular mechanism underlying membrane protein topogenesis. Visualization of a polytopic membrane protein during SecY-mediated membrane insertion.,Bischoff L, Wickles S, Berninghausen O, van der Sluis EO, Beckmann R Nat Commun. 2014 Jun 10;5:4103. doi: 10.1038/ncomms5103. PMID:24912953 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Bacteriorhodopsin 3D structures Preprotein translocase