GRP78 Endoplasmic reticulum chaperone that plays a key role in protein folding and quality control in the endoplasmic reticulum lumen. 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. Acts as a key repressor of the ERN1/IRE1-mediated unfolded protein response (UPR). 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. Accumulation of misfolded protein in the endoplasmic reticulum causes release of HSPA5/BiP from ERN1/IRE1, allowing homodimerization and subsequent activation of ERN1/IRE1. 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. Belongs to the heat shock protein 70 family. Note: This description may include information from UniProtKB.

Protein type: Chaperone; Heat shock protein

Chromosomal Location of human Ortholog: 9q33.3

Cellular Component: cell surface; cytoplasm; cytosol; endoplasmic reticulum; endoplasmic reticulum chaperone complex; endoplasmic reticulum lumen; endoplasmic reticulum membrane; endoplasmic reticulum-Golgi intermediate compartment; intracellular membrane-bounded organelle; melanosome; membrane; midbody; mitochondrion; nucleus; plasma membrane; protein-containing complex

Molecular Function: ATP binding; ATP hydrolysis activity; ATP-dependent protein folding chaperone; calcium ion binding; enzyme binding; heat shock protein binding; misfolded protein binding; protein binding; protein domain specific binding; protein folding chaperone; protein-folding chaperone binding; ribosome binding; ubiquitin protein ligase binding; unfolded protein binding

Biological Process: cellular response to glucose starvation; cellular response to interleukin-4; cerebellar Purkinje cell layer development; cerebellum structural organization; chaperone cofactor-dependent protein refolding; endoplasmic reticulum unfolded protein response; ER overload response; maintenance of protein localization in endoplasmic reticulum; negative regulation of apoptotic process; negative regulation of IRE1-mediated unfolded protein response; negative regulation of protein-containing complex assembly; negative regulation of transforming growth factor beta receptor signaling pathway; positive regulation of cell migration; positive regulation of protein ubiquitination; positive regulation of transcription from RNA polymerase II promoter in response to endoplasmic reticulum stress; post-translational protein targeting to membrane, translocation; protein folding in endoplasmic reticulum; protein refolding; regulation of ATF6-mediated unfolded protein response; regulation of IRE1-mediated unfolded protein response; regulation of PERK-mediated unfolded protein response; regulation of protein folding in endoplasmic reticulum; ubiquitin-dependent ERAD pathway

Reference #: P11021 (UniProtKB)

Alt. Names/Synonyms: 78 kDa glucose-regulated protein; Binding-immunoglobulin protein; BiP; Endoplasmic reticulum chaperone BiP; Endoplasmic reticulum lumenal Ca(2+)-binding protein grp78; epididymis secretory sperm binding protein Li 89n; FLJ26106; glucose-regulated protein, 78kDa; GRP-78; GRP78; Heat shock 70 kDa protein 5; heat shock 70kD protein 5 (glucose-regulated protein, 78kD); heat shock 70kDa protein 5 (glucose-regulated protein, 78kDa); Heat shock protein 70 family protein 5; heat shock protein family A (Hsp70) member 5; Heat shock protein family A member 5; Heat-shock 70kD protein-5 (glucose-regulated protein, 78kD); HEL-S-89n; HSP70 family protein 5; HSPA5; Immunoglobulin heavy chain-binding protein; MIF2

Gene Symbols: HSPA5

Molecular weight: 72,333 Da

Basal Isoelectric point: 5.07 Predict pI for various phosphorylation states

Protein-Specific Antibodies, siRNAs or Recombinant Proteins from Cell Signaling Technology^®

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GRP78

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