1xb0

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Revision as of 17:56, 12 November 2007

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spinqualitylabelsall models 1xb0, resolution 2.2Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Structure of the BIR domain of IAP-like protein 2

Overview

Several IAP (inhibitor of apoptosis) proteins regulate cell fate, decisions, and the X-linked IAP (XIAP) does so in part by inhibiting, caspases, proteases that execute the apoptotic pathway. A tissue-specific, homologue of XIAP, known as ILP2 (IAP-like protein 2), has previously been, implicated in the control of apoptosis in the testis by direct inhibition, of caspase 9. In examining this protein we found that the putative caspase, 9 interaction domain is a surprisingly weak inhibitor and is also, conformationally unstable. Comparison with the equivalent domain in XIAP, demonstrated that the instability is due to the lack of a linker segment, N-terminal to the inhibitory BIR (baculovirus IAP repeat) domain. Fusion, of a 9-residue linker from XIAP to the N-terminus of ILP2 restored tight, caspase 9 inhibition, dramatically increased conformational stability and, allowed crystallization of the ILP2 BIR domain in a form strikingly, similar to the XIAP third BIR domain. We conclude that ILP2 is an unstable, protein, and cannot inhibit caspase 9 in a physiological way on its own., We speculate that ILP2 requires assistance from unidentified cellular, factors to be an effective inhibitor of apoptosis in vivo.

About this Structure

1XB0 is a Protein complex structure of sequences from Homo sapiens with ZN as ligand. Full crystallographic information is available from OCA.

Reference

The BIR domain of IAP-like protein 2 is conformationally unstable: implications for caspase inhibition., Shin H, Renatus M, Eckelman BP, Nunes VA, Sampaio CA, Salvesen GS, Biochem J. 2005 Jan 1;385(Pt 1):1-10. PMID:15485395

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