5e85 | pdb_00005e85
isolated SBD of BiP
Structural highlights
DiseaseBIP_HUMAN Autoantigen in rheumatoid arthritis.[1] FunctionBIP_HUMAN Endoplasmic reticulum chaperone that plays a key role in protein folding and quality control in the endoplasmic reticulum lumen (PubMed:2294010, PubMed:23769672, PubMed:23990668, PubMed:28332555). Involved in the correct folding of proteins and degradation of misfolded proteins via its interaction with DNAJC10/ERdj5, probably to facilitate the release of DNAJC10/ERdj5 from its substrate (By similarity). Acts as a key repressor of the ERN1/IRE1-mediated unfolded protein response (UPR) (PubMed:1550958, PubMed:19538957). In the unstressed endoplasmic reticulum, recruited by DNAJB9/ERdj4 to the luminal region of ERN1/IRE1, leading to disrupt the dimerization of ERN1/IRE1, thereby inactivating ERN1/IRE1 (By similarity). Accumulation of misfolded protein in the endoplasmic reticulum causes release of HSPA5/BiP from ERN1/IRE1, allowing homodimerization and subsequent activation of ERN1/IRE1 (By similarity). Plays an auxiliary role in post-translational transport of small presecretory proteins across endoplasmic reticulum (ER). May function as an allosteric modulator for SEC61 channel-forming translocon complex, likely cooperating with SEC62 to enable the productive insertion of these precursors into SEC61 channel. Appears to specifically regulate translocation of precursors having inhibitory residues in their mature region that weaken channel gating.[UniProtKB:G3I8R9][UniProtKB:P20029][2] [3] [4] [5] [6] [7] [8] Publication Abstract from PubMedBinding immunoglobulin protein (BiP), an essential and ubiquitous Hsp70 chaperone in the ER, plays a key role in protein folding and quality control. BiP contains two functional domains: a nucleotide-binding domain (NBD) and a substrate-binding domain (SBD). NBD binds and hydrolyzes ATP; the substrates for SBD are extended polypeptides. ATP binding allosterically accelerates polypeptide binding and release. Although crucial to the chaperone activity, the molecular mechanisms of polypeptide binding and allosteric coupling of BiP are poorly understood. Here, we present crystal structures of an intact human BiP in the ATP-bound state, the first intact eukaryotic Hsp70 structure, and isolated BiP-SBD with a peptide substrate bound representing the ADP-bound state. These structures and our biochemical analysis demonstrate that BiP has a unique NBD-SBD interface that is highly conserved only in eukaryotic Hsp70s found in the cytosol and ER to fortify its ATP-bound state and promote the opening of its polypeptide-binding pocket. Close and Allosteric Opening of the Polypeptide-Binding Site in a Human Hsp70 Chaperone BiP.,Yang J, Nune M, Zong Y, Zhou L, Liu Q Structure. 2015 Dec 1;23(12):2191-203. doi: 10.1016/j.str.2015.10.012. Epub 2015 , Nov 19. PMID:26655470[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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