Comments: |
Caspase-9 is an initiator caspase, as are caspase -2 (EC 3.4.22.55), caspase-8 (EC 3.4.22.61) and caspase-10 (EC 3.4.22.63) [1]. Caspase-9 contains a caspase-recruitment domain (CARD) in its N-terminal prodomain, which plays a role in procaspase activation [1]. An alternatively spliced version of caspase-9 also exists, caspase-9S, that inhibits apoptosis, similar to the situation found with caspase-2 [1]. Phosphorylation of caspase-9 from some species by Akt, a serine-threonine protein kinase, inhibits caspase activity in vitro and caspase activation in vivo [1]. The activity of caspase-9 is increased dramatically upon association with the apoptosome but the enzyme can be activated without proteolytic cleavage [2,3]. Procaspase-3 is the enzyme’s physiological substrate [2]. Belongs in peptidase family C14. |
References: |
1. |
Chang, H.Y. and Yang, X. Proteases for cell suicide: functions and regulation of caspases. Microbiol. Mol. Biol. Rev. 64 (2000) 821–846. [PMID: 11104820] |
2. |
Yin, Q., Park, H.H., Chung, J.Y., Lin, S.C., Lo, Y.C., da Graca, L.S., Jiang, X. and Wu, H. Caspase-9 holoenzyme is a specific and optimal procaspase-3 processing machine. Mol. Cell. 22 (2006) 259–268. [DOI] [PMID: 16630893] |
3. |
Boatright, K.M., Renatus, M., Scott, F.L., Sperandio, S., Shin, H., Pedersen, I.M., Ricci, J.E., Edris, W.A., Sutherlin, D.P., Green, D.R. and Salvesen, G.S. A unified model for apical caspase activation. Mol. Cell. 11 (2003) 529–541. [DOI] [PMID: 12620239] |
4. |
Salvesen, G.S. and Boatright, K.M. Caspase-9. In: Barrett, A.J., Rawlings, N.D. and Woessner, J.F. (Ed.), Handbook of Proteolytic Enzymes, 2nd edn, Elsevier, London, 2004, pp. 1296–1298. |
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