XAF1

This gene encodes a protein which binds to and counteracts the inhibitory effect of a member of the IAP (inhibitor of apoptosis) protein family. IAP proteins bind to and inhibit caspases which are activated during apoptosis. The proportion of IAPs and proteins which interfere with their activity, such as the encoded protein, affect the progress of the apoptosis signaling pathway. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Feb 2012]

Full Name

XIAP Associated Factor 1

Function

Seems to function as a negative regulator of members of the IAP (inhibitor of apoptosis protein) family. Inhibits anti-caspase activity of BIRC4. Induces cleavage and inactivation of BIRC4 independent of caspase activation. Mediates TNF-alpha-induced apoptosis and is involved in apoptosis in trophoblast cells. May inhibit BIRC4 indirectly by activating the mitochondrial apoptosis pathway. After translocation to mitochondria, promotes translocation of BAX to mitochondria and cytochrome c release from mitochondria. Seems to promote the redistribution of BIRC4 from the cytoplasm to the nucleus, probably independent of BIRC4 inactivation which seems to occur in the cytoplasm. The BIRC4-XAF1 complex mediates down-regulation of BIRC5/survivin; the process requires the E3 ligase activity of BIRC4. Seems to be involved in cellular sensitivity to the proapoptotic actions of TRAIL. May be a tumor suppressor by mediating apoptosis resistance of cancer cells.

Biological Process

Biological Process apoptotic process Source:UniProtKB-KW
Biological Process response to interferon-beta Source:BHF-UCL1 Publication

Cellular Location

Cytoplasm
Nucleus
Mitochondrion
Found in the cytoplasm and nucleus of placental syncytiotrophoblasts. Translocates to mitochondria upon TNF-alpha treatment.
Isoform 1
Nucleus
Isoform 5
Nucleus