Ca2+-dependent Cysteine Proteases

In higher organisms, calpain superfamily contains 16 independent genes that modulate cellular function. Out of them, 14 are Ca2+-dependent cysteine proteases. The other two encode smaller regulatory proteins that... 

Sustained cytosolic Ca2+ overload usually results in a different route leading to cell death. It mainly relies on the activation of the calcium/calmodulin (CaM)-dependent phosphatase, calcineurin. Calcineurin-catalyzed dephosphorylation promotes apoptosis by regulating the activity of a number of downstream targets, including the pro-apoptotic Bcl-2 family member, Bad (Wang, et al., 1999), and transcription factors of the NFAT (nuclear factor of activated T cells) family (Rao, et al., 1997). There are also other Ca2+-dependent enzymes contributing to the apoptotic events, and they include several DNA-degrading endonucleases (Robertson, et al., 2000) and Ca2+-activated cystein proteases of the calpain family essential for the enzymatic activation of the crucial pro-apoptotic effectors (Altznauer, et al., 2004). 

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