Livin (D61D1) XP^® Rabbit mAb #5471

The inhibitor of apoptosis protein (IAP) family consists of an evolutionarily conserved group of apoptosis inhibitors containing a conserved 70 amino acid BIR (baculovirus inhibitor repeat) domain (1,2). Human members of this family include c-IAP1, c-IAP2, XIAP, survivin, livin, and NAIP. Overexpression of IAP family members, particularly survivin and livin, in cancer cell lines and primary tumors suggests an important role for these proteins in cancer progression (3-5). In general, the IAP proteins function through direct interactions to inhibit the activity of several caspases, including caspase-3, caspase-7, and caspase-9 (5,6). In addition, binding of IAP family members to the mitochondrial protein Smac blocks their interaction with caspase-9, thereby allowing the processing and activation of the caspase (2).
Livin (BIRC7/ML-IAP) is a potent anti-apoptotic IAP family member containing a single BIR domain and RING finger motif that is highly expressed in human melanomas and absent in normal tissues (5,7). It is localized in the nucleus and diffusely in the cytoplasm (5). The livin gene encodes two splicing variants, a 298 amino acid isoform (α) and a 280 amino acid form (β), with different biological activity to various apoptotic stimuli (8). In addition to directly inhibiting caspase activity, livin can promote the degradation of the pro-apoptotic protein Smac through the ubiquitin-proteasome pathway (9). Its preferential expression in tumor cells, along with several studies showing that downregulation of livin can promote apoptosis, has led to studies analyzing the use of livin in cancer therapy (10).