The Ribosome-Sec61 Translocon Complex Forms a Cytosolically Restricted Environment for Early Polytopic Membrane Protein Folding.

ABSTRACT: Transmembrane topology of polytopic membrane proteins (PMPs) is established in the endoplasmic reticulum (ER) by the ribosome Sec61-translocon complex (RTC) through iterative cycles of translocation initiation and termination. It remains unknown, however, whether tertiary folding of transmembrane domains begins after the nascent polypeptide integrates into the lipid bilayer or within a proteinaceous environment proximal to translocon components. To address this question, we used cysteine scanning mutagenesis to monitor aqueous accessibility of stalled translation intermediates to determine when, during biogenesis, hydrophilic peptide loops of the aquaporin-4 (AQP4) water channel are delivered to cytosolic and lumenal compartments. Results showed that following ribosome docking on the ER me

SUBMITTER: Patterson MA 

PROVIDER: S-EPMC4661407 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature