Table 1.

Some characteristics of the eight human inhibitors of apoptosis (IAP) family members

IAP family members	Size (kDa)	Chromosome positions	Number of domains	Caspase specificity
XIAP (ILP1)	57	Xq25	BIR: 3 RING: 1	Caspase 3, 7, 9
cIAP1	70	11q22-q23	BIR: 3 RING: 1 CARD: 1	Caspase 3, 7, 9
cIAP2	68	11q22-q23	BIR: 3 RING: 1 CARD: 1	Caspase 3, 7, 9
LIVIN (ML-IAP)	31	20q13.3	BIR: 1 RING: 1	Caspase 3, 7, 9
ILP2#	?	19q 13.3-q13.4	BIR: 1 RING: 1	Caspase 9
NAIP*	156	5q13.1	BIR: 3 RING: 0	Caspase 3, 7
Survivin	16.5	17q25	BIR: 1 RING: 0	Caspase 3, 7
BRUCE	528	2p21-p22	BIR: 1 RING: 0	Caspase 3, 7

^*The first characterized mammalian IAP.

^#The most recently identified IAP (a tissue-specific homologue of XIAP).

BIR, baculovirus IAP repeat; RING, really interesting new gene; CARD, caspase recruitment domain; XIAP, X-linked inhibitors of apoptosis protein; cIAP1, cellular inhibitors of apoptosis protein 1; cIAP2, cellular inhibitors of apoptosis protein 2; ILP2, IAP-like protein 2; NAIP, neuronal apoptosis inhibitory protein;. BRUCE, BIR repeat-containing ubiquitin-conjugating enzyme.