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Updated: Aug 21, 2026

Co-Translational Insertion of Membrane Proteins into Preformed Nanodiscs
Published on: November 19, 2020
The cotranslational integration of membrane proteins into the phospholipid bilayer is a multistep process
1Department of Medical Biochemistry & Genetics, Texas A&M University Health Science Center, College Station 77843-1114, USA.
Abstract:
During the cotranslational integration of a nascent protein into the endoplasmic reticulum membrane, the transmembrane (TM) sequence moves out of an aqueous pore formed by Sec61alpha, TRAM, and other proteins and into the nonpolar lipid bilayer. Photocross-linking reveals that this movement involves the sequential passage of the TM domain through three different proteinaceous environments: one adjacent to Sec61alpha and TRAM and two adjacent to TRAM that place different restrictions on TM domain movement. In addition, the TM sequence is not allowed to diffuse into the bilayer from the final TRAM-proximal site until translation terminates. Cotranslational integration is therefore linked to translation and occurs via an ordered multistep pathway at an endoplasmic reticulum site that is multilayered both structurally and functionally.
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