The inhibitor of apoptosis domain -- also known as IAP repeat,
Baculovirus
Inhibitor of apoptosis protein
Repeat, or BIR -- is a
structural motif found in
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
s with roles in
apoptosis,
cytokine
Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrin ...
production, and
chromosome segregation
Chromosome segregation is the process in eukaryotes by which two sister chromatids formed as a consequence of DNA replication, or paired homologous chromosomes, separate from each other and migrate to opposite poles of the nucleus. This segregati ...
.
Proteins containing BIR are known as
inhibitor of apoptosis
Inhibitors of apoptosis are a group of proteins that mainly act on the intrinsic pathway that block programmed cell death, which can frequently lead to cancer or other effects for the cell if mutated or improperly regulated. Many of these inhibit ...
proteins (IAPs), or BIR-containing proteins (BIRPs or BIRCs), and include BIRC1 (
NAIP),
BIRC2
Baculoviral IAP repeat-containing protein 2 (also known as cIAP1) is a protein that in humans is encoded by the ''BIRC2'' gene.
Function
cIAP1 is a member of the Inhibitor of Apoptosis family that inhibit apoptosis by interfering with the acti ...
(cIAP1),
BIRC3
Baculoviral IAP repeat-containing protein3 (also known as cIAP2) is a protein that in humans is encoded by the ''BIRC3'' gene.
cIAP2 is a member of the inhibitor of apoptosis family that inhibit apoptosis by interfering with the activation of ca ...
(cIAP2), BIRC4 (
xIAP
X-linked inhibitor of apoptosis protein (XIAP), also known as inhibitor of apoptosis protein 3 (IAP3) and baculoviral IAP repeat-containing protein 4 (BIRC4), is a protein that stops apoptotic cell death. In humans, this protein (XIAP) is produ ...
), BIRC5 (
survivin) and
BIRC6
Baculoviral IAP repeat-containing protein 6 is a protein that in humans is encoded by the ''BIRC6'' gene.
Function
This gene encodes a protein with a BIR (baculoviral inhibition of apoptosis protein repeat) domain and a UBCc (ubiquitin-conjugat ...
.
BIR domains belong to the
zinc-finger
A zinc finger is a small protein structural motif that is characterized by the coordination of one or more zinc ions (Zn2+) in order to stabilize the fold. It was originally coined to describe the finger-like appearance of a hypothesized struc ...
domain family and characteristically have a number of invariant
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha a ...
residues, including 3 conserved
cysteines and one conserved
histidine
Histidine (symbol His or H) is an essential amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated –NH3+ form under biological conditions), a carboxylic acid group (which is in the d ...
, which coordinate a
zinc
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
ion.
They are typically composed of 4-5
alpha helices
The alpha helix (α-helix) is a common motif in the secondary structure of proteins and is a right hand-helix conformation in which every backbone N−H group hydrogen bonds to the backbone C=O group of the amino acid located four residues ear ...
and a three-stranded
beta sheet.
External links
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References
{{InterPro content, IPR001370
Protein structural motifs
Protein domains