Two redundant systems maintain levels of resident proteins within the yeast endoplasmic reticulum.
The Saccharomyces cerevisiae gene ERD2 is responsible for the retrieval of lumenal resident proteins of the endoplasmic reticulum (ER) lost to the next secretory compartment. Previous studies have suggested that the retrieval of proteins by ERD2 is not essential. Here, we find that ERD2-mediated retrieval is not an essential process only because, on its failure, a second inducible system acts to maintain levels of ER proteins. The second system is controlled by the ER membrane-bound kinase encoded by IRE1. We conclude that IRE1 and ERD2 together maintain normal concentrations of resident proteins within the ER.
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Lewis Thomas Laboratory, Princeton University, NJ 08544, USA.
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D002451:Cell Compartmentation; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D005800:Genes, Fungal; D005804:Genes, Lethal; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D015151:Immunoblotting; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins; D016296:Mutagenesis; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D018000:Receptors, Peptide; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins
C064922:ERD2 protein, S cerevisiae; D005656:Fungal Proteins; D018840:HSP70 Heat-Shock Proteins; C060153:KAR2 protein, yeast; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D018000:Receptors, Peptide; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; C082863:IRE1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases