Binding immunoglobulin protein

From Wikipedia, the free encyclopedia

Heat shock 70kDa protein 5 (glucose-regulated protein, 78kDa)

Identifiers

HSPA5; MIF2; BIP; FLJ26106; GRP78

External IDs

OMIM: 138120 MGI: 95835 HomoloGene: 3908

Gene ontology
Molecular Function:	• nucleotide binding • calcium ion binding • ATP binding • protein binding, bridging • ribosome binding • caspase inhibitor activity • unfolded protein binding
Cellular Component:	• nucleus • endoplasmic reticulum • endoplasmic reticulum lumen • ER-Golgi intermediate compartment • caspase complex • cell surface • integral to endoplasmic reticulum membrane • perinuclear region of cytoplasm
Biological Process:	• anti-apoptosis • ER overload response • negative regulation of caspase activity

RNA expression pattern

More reference expression data

Orthologs

Human

Mouse

Refseq

NM_005347 (mRNA)
NP_005338 (protein)

NM_022310 (mRNA)
NP_071705 (protein)

Location

Chr 9: 127.04 - 127.04 Mb

Chr 2: 34.59 - 34.6 Mb

Pubmed search

[1]

[2]

Binding immunoglobulin protein (BiP) (also called glucose regulated protein 78, Grp78) is a molecular chaperone that uses ATP/ADP cycling to regulate protein folding by the Protein Disulfide Isomerase (PDI) family of proteins. It is a 78kDa glucose-regulated heat shock protein and is involved in unfolded protein response. HSPA5 is its human gene. It binds to immunoglobulin heavy chain.

[edit] Mechanism

When the nucleotide-binding domain of BiP interacts with ATP, its substrate-binding domain can interact with unfolded/misfolded protein. Subsequent ATP hydrolysis acts to strengthen the interaction between BiP and the unfolded/misfolded protein. Under these conditions PDI can then work to promote disulfide oxidation and rearrangement until the correct protein conformation is achieved. ADP/ATP exchange ends the interaction of BiP with the protein and thus PDI's work is halted as well.

Once the correct protein structure is achieved it is no longer a candidate for BiP binding.

When Chinese hamster K12 cells are starved of glucose, the synthesis of several proteins, called glucose-regulated proteins (GRPs), is markedly increased. Hendershot et al. (1994) pointed out that one of these, GRP78 (HSPA5), also referred to as 'immunoglobulin heavy chain-binding protein' (BiP), is a member of the heat-shock protein-70 (HSP70) family and is involved in the folding and assembly of proteins in the endoplasmic reticulum (ER). Because so many ER proteins interact transiently with GRP78, it may play a key role in monitoring protein transport through the cell.[supplied by OMIM]^[1]