BIR

Baculoviral inhibition of apoptosis protein repeat
BIR
SMART accession number:SM00238
Description: Domain found in inhibitor of apoptosis proteins (IAPs) and other proteins. Acts as a direct inhibitor of caspase enzymes.
Interpro abstract (IPR001370):

The baculovirus inhibitor of apoptosis protein repeat (BIR) is a domain of tandem repeats separated by a variable length linker that seems to confer cell death-preventing activity [(PUBMED:8139034), (PUBMED:8552191)]. The BIR domains characterise the Inhibitor of Apoptosis (IAP) family of proteins (MEROPS proteinase inhibitor family I32, clan IV) that suppress apoptosis by interacting with and inhibiting the enzymatic activity of both initiator and effector caspases (MEROPS peptidase family C14, IPR002398).

The first-recognised members of family MEROPS inhibitor family I32 were viral proteins that inhibited the apoptosis of infected cells: Cp-IAP from Cydia pomonella granulosis virus (CpGV) [(PUBMED:8445726)] and Op-IAP from Orgyia pseudotsugata multicapsid polyhedrosis virus(OpMNPV) [(PUBMED:8139034)]. Several distinct mammalian IAPs including XIAP, c-IAP1, c-IAP2, and ML-IAP, have since been identified, and they all exhibit antiapoptotic activity in cell culture. The functional unit in each IAP protein is the baculoviral IAP repeat (BIR), which contains approximately 80 amino acids folded around a zinc atom. Most mammalian IAPs have more than one BIR domain, with the different BIR domains performing distinct functions. For example, in XIAP, the third BIR domain (BIR3) potently inhibits the catalytic activity of caspase-9, whereas the linker sequences immediately preceding the second BIR domain (BIR2) selectively targets caspase-3 or -7 [(PUBMED:18992220)].

This entry represents the BIR domain, found in inhibitor of apoptosis proteins (IAPs) and also known as IAP repeat. BIR is also found in other proteins known as BIR-domain-containing proteins (BIRPs), such as Survivin [(PUBMED:11516343)].

GO component:intracellular (GO:0005622)
Family alignment:
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There are 1128 BIR domains in 652 proteins in SMART's nrdb database.

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