Figure 2.

Sequence alignment of BIR domains. The sequences of the described BIR3 and BIR2 domains from human cIAP2 and NAIP are compared with the corresponding BIR domains from XIAP. The ML-IAP BIR domain structure was used as search model for molecular replacement. Colour markers: red triangles, Zn²⁺-chelating residues; green triangles, residues of high importance for IBM interaction (see text for details); blue triangles, conserved residues lining a hydrophobic cavity at the P1′ binding position.