Cer1p, a novel Hsp70-related protein required for posttranslational endoplasmic reticulum translocation in yeast.
Proteins enter the secretory pathway by translocation across the endoplasmic reticulum (ER) membrane. In Saccharomyces cerevisiae, import of proteins into the ER occurs both cotranslationally and posttranslationally. Presumably, the cotranslational targeting to the ER membrane is directed by the signal recognition particle, as demonstrated in other eukaryotic systems. The deletion of a gene, called CER1, inhibits the translocation of proteins that enter the ER posttranslationally, but not those that enter cotranslationally. This translocation defect is more pronounced at lower temperatures. A strain possessing a null mutation of CER1 in combination with a kar2 temperature-sensitive mutation displays synthetic growth defects, whereas overexpression of the ER DnaJ homolog Scj1p suppresses the translocation defect in cer1Delta strains. CER1 is predicted to encode a 100-kDa polypeptide, residing in the ER lumen that is related to the hsp70 family of molecular chaperones.
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Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, USA. gflynn@molbio.uoregon.edu
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D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry* / Q000378:metabolism; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry*; D006360:Heat-Shock Proteins / Q000378:metabolism; D018832:Molecular Chaperones / Q000737:chemistry*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010940:Plant Proteins / Q000737:chemistry*; D011499:Protein Processing, Post-Translational; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D013696:Temperature
D029681:Arabidopsis Proteins; C101547:CER protein, Arabidopsis; D005656:Fungal Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C060153:KAR2 protein, yeast; D018832:Molecular Chaperones; D010940:Plant Proteins; C067634:SCJ1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins