Figure 1: Schematic representation of human IAPs. IAPs contain between one and three Baculovirus IAP repeat (BIR) domains, a 70-80 amino acid Zinc-binding motif. Five of the 8 IAPs possess a carboxy-terminal RING (really interesting new gene) domain that functions as an E3 ligase, capable of self-ubiquitination and ubiquitination of associated proteins. Bruce lacks a RING domain but possesses an Ubiquitin-Conjugating Domain (UBC) that can induce ubiquitination. XIAP and cIAPs have an Ubiquitin-Associated (UBA) ubiquitin-binding domain that is important for their signalling function [67,98]. In addition cIAP1 and cIAP2 contain a Caspase Recruitment Domain (CARD) that can mediate homotypic interactions [99]. NAIP possesses a LRR (Leucine-Rich Repeat) and a NOD (nucleotide-binding oligomerisation domain), which have been implicated in microbial pathogen recognition. Survivin contains a COIL (coil-coiled) domain, which is involved in binding to chromosomal paasenger proteins INCENP and borealin.