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

During the mating of yeast Saccharomyces cerevisiae, two haploid nuclei fuse to produce a diploid nucleus. This process requires the functions of BiP/Kar2p, a member of the Hsp70 family in the endoplasmic reticulum, and its partner protein, Jem1p. To investigate further the role of BiP and Jem1p in nuclear fusion, we screened for partner proteins for Jem1p by the yeast two-hybrid system and identified Nep98p. Nep98p is an essential integral membrane protein of the nuclear envelope and is enriched in the spindle pole body (SPB), the sole microtubule-organizing center in yeast. Temperature-sensitive nep98 mutant cells contain abnormal SPBs lacking the half-bridge, suggesting the essential role of Nep98p in the organization of the normal SPB. Additionally, nep98 mutant cells show defects in mitotic nuclear division and nuclear fusion during mating. Because Jem1p is not required for nuclear division, Nep98p probably has dual functions in Jem1p-dependent karyogamy and in Jem1p-independent nuclear division.
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PMID:Nep98p is a component of the yeast spindle pole body and essential for nuclear division and fusion. 1249 74

Protein localization within cells regulates accessibility for interactions with co-factors and substrates. The endoplasmic reticulum (ER) BiP co-factor ERdj4 is up-regulated by ER stress and has been implicated in ER-associated degradation (ERAD) of multiple unfolded secretory proteins. Several other ERdj family members tend to interact selectively with nascent proteins, presumably because those ERdj proteins associate with the Sec61 translocon that facilitates entry of nascent proteins into the ER. How ERdj4 selects and targets terminally misfolded proteins for destruction remains poorly understood. In this study, we determined properties of ERdj4 that might aid in this function. ERdj4 was reported to retain its signal sequence and to be resistant to mild detergent extraction, suggesting that it was an integral membrane protein. However, live cell photobleaching analyses of GFP-tagged ERdj4 revealed that the protein exhibits diffusion coefficients uncommonly high for an ER integral membrane protein and more similar to the mobility of a soluble luminal protein. Biochemical characterization established that the ERdj4 signal sequence is cleaved to yield a soluble protein. Importantly, we found that both endogenous and overexpressed ERdj4 associate with the integral membrane protein, Derlin-1. Our findings now directly link ERdj4 to the ERAD machinery and suggest a model in which ERjd4 could help recruit clients from throughout the ER to ERAD sites.
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PMID:ERdj4 protein is a soluble endoplasmic reticulum (ER) DnaJ family protein that interacts with ER-associated degradation machinery. 2226 25


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