Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P11021 (BiP)
 2,049 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

DnaJ-like proteins are functional partners for Hsp70 molecular chaperones. Complete nucleotide sequencing of yeast chromosome X has revealed that an open reading frame YJL073w encodes a novel member of the DnaJ-like protein family. The open reading frame represents a protein of 692 amino acids with a J-domain and one putative membrane-spanning segment. An epitope-tagged version of the protein was anchored in the endoplasmic reticulum (ER) membrane and its J-domain faced the ER lumen. We therefore propose to designate this gene JEM1 (DnaJ-like protein of the ER membrane) and to designate its gene product JEM1p. The JEM1 gene is not essential for cell growth, but double disruption of the JEM1 gene and the SCJ1 gene, which encodes another DnaJ-like protein in the ER lumen, causes growth arrest at elevated temperature. The Deltajem1 mutant is defective in nuclear fusion, karyogamy, during mating. A mutant JEM1p carrying a mutation in the highly conserved His-Pro-Asp sequence in the J-domain could not complement either temperature-sensitive growth of the Deltajem1 Deltascj1 double mutant or defects in karyogamy of the Deltajem1 mutant. JEM1p likely assists the functions of BiP, Hsp70 in the ER, including karyogamy.
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PMID:The yeast JEM1p is a DnaJ-like protein of the endoplasmic reticulum membrane required for nuclear fusion. 914 90

Endoplasmic reticulum (ER)-associated degradation (ERAD) is the process by which aberrant proteins in the ER lumen are exported back to the cytosol and degraded by the proteasome. Although ER molecular chaperones are required for ERAD, their specific role(s) in this process have been ill defined. To understand how one group of interacting lumenal chaperones facilitates ERAD, the fates of pro-alpha-factor and a mutant form of carboxypeptidase Y were examined both in vivo and in vitro. We found that these ERAD substrates are stabilized and aggregate in the ER at elevated temperatures when BiP, the lumenal Hsp70 molecular chaperone, is mutated, or when the genes encoding the J domain-containing proteins Jem1p and Scj1p are deleted. In contrast, deletion of JEM1 and SCJ1 had little effect on the ERAD of a membrane protein. These results suggest that one role of the BiP, Jem1p, and Scj1p chaperones is to maintain lumenal ERAD substrates in a retrotranslocation-competent state.
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PMID:Molecular chaperones in the yeast endoplasmic reticulum maintain the solubility of proteins for retrotranslocation and degradation. 1138 Oct 90