Ssh1p determines the translocation and dislocation capacities of the yeast endoplasmic reticulum.
Sec61p is required both for protein translocation and dislocation across the membrane of the endoplasmic reticulum (ER). However, the cellular role of the Sec61p homolog Ssh1p has not been clearly defined. We show that deltassh1 mutant cells have strong defects in both SRP-dependent and -independent translocation. Moreover, these cells were also found to be induced for the unfolded protein response and to be defective in dislocation of a misfolded ER protein. In addition, deltassh1 mutant cells rapidly became respiratory deficient. The other defects discussed above were suppressed in the respiratory-deficient state or under conditions where the rate of polypeptide translation was artificially reduced. These data identify Ssh1p as a component of a second, functionally distinct translocon in the yeast ER membrane.
Wilkinson
B M
BM
School of Biological Sciences, University of Manchester, United Kingdom.
Tyson
J R
JR
Stirling
C J
CJ
D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins; D010641:Phenotype; D017510:Protein Folding; D021381:Protein Transport / Q000502:physiology*; D000069816:SEC Translocation Channels; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D018271:Signal Recognition Particle / Q000378:metabolism
D000935:Antifungal Agents; D005656:Fungal Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D000069816:SEC Translocation Channels; C499383:SEC61 protein, S cerevisiae; C489551:SEC65 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D018271:Signal Recognition Particle; D003513:Cycloheximide