Baculoviral IAP repeat-containing protein 2 is a protein in humans that is encoded by BIRC2 gene. Multi-functional protein which regulates not only caspases and apoptosis, but also modulates inflammatory signaling and immunity, mitogenic kinase signaling, and cell proliferation, as well as cell invasion and metastasis. Acts as an E3 ubiquitin-protein ligase regulating NF-kappa-B signaling and regulates both canonical and non-canonical NF-kappa-B signaling by acting in opposite directions.
Baculoviral inhibitors of apoptosis repeat-containing protein 2 (BIRC2), also called cellular inhibitors of apoptosis 1 (cIAP1), is a protein in humans that is encoded by BIRC2 gene. cIAP1 contains three tandem amino-terminal BIR domains, a zinc-binding RING domain at the carboxy terminus, and a caspase-recruitment (CARD) domain in the linker region between the BIR and the RING (Really Interesting New Gene) domains. Among the domains of cIAP1, the RING domain exerts an important role in preventing apoptosis. This domain acts as an E3 ligase by binding to E2 ubiquitin-conjugating enzymes (UBCs) and catalyzing the transfer of ubiquitin onto target proteins such as caspases, ultimately inhibiting apoptosis. The CARD domain of cIAP1 is reported to emit a functional nuclear export signal that seems to be important for cell differentiation. BIRC2 protein also mediates various cellular functions, including the regulation of signaling and inflammation. Rothe M et al. have uncovered that BIRC2 and another IAP family member BIRC3, together with TRAF2, are key components of the TNF signaling pathway that are necessary for TNF-mediated NF-kappa B activation. On the contrary, BIRC2, and BIRC3 act as a molecular brake to rein inactivation of the JNK signaling pathway. The amplification and increased levels of cIAP1 have been observed in several cancer types and are required for tumorigenesis in vivo. cIAP1 deprivation, caused by IAP antagonist drugs or cIAP1 deletion, might augment physiological TNF-receptor apoptotic signaling, thus resulting in enhanced tumor cell death. It suggests a promising cancer treatment by using some IAP antagonist compounds.