ER-localized Shr3 is a selective co-translational folding chaperone necessary for amino acid permease biogenesis.

Proteins with multiple membrane-spanning segments (MS) co-translationally insert into the endoplasmic reticulum (ER) membrane of eukaryotic cells. Shr3, an ER membrane-localized chaperone in Saccharomyces cerevisiae, is required for the functional expression of a family of 18 amino acid permeases (AAP) comprised of 12 MS. We have used comprehensive scanning mutagenesis ...
and deletion analysis of Shr3 combined with a modified split-ubiquitin approach to probe chaperone-substrate interactions in vivo. Shr3 selectively interacts with nested C-terminal AAP truncations in marked contrast to similar truncations of non-Shr3 substrate sugar transporters. Shr3-AAP interactions initiate with the first four MS of AAP and successively strengthen but weaken abruptly when all 12 MS are present. Shr3-AAP interactions are based on structural rather than sequence-specific interactions involving membrane and luminal domains of Shr3. The data align with Shr3 engaging nascent N-terminal chains of AAP, functioning as a scaffold to facilitate folding as translation completes.
Mesh Terms:
Amino Acid Transport Systems, Biological Transport, Endoplasmic Reticulum, Molecular Chaperones, Protein Folding, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Vesicular Transport Proteins
J Cell Biol
Date: Sep. 04, 2023
Download Curated Data For This Publication
246625
Switch View:
  • Interactions 6