All cut up! The consequences of calpain activation on platelet function.

The Ca(2+)-activated proteases or calpains, play a crucial role in a spectrum of physiological processes such as cytoskeletal remodeling, cellular signaling, cell migration, apoptosis, cell survival and platelet activation, by the proteolytic cleavage of target proteins. Rather than eliciting protein degradation the calpains are responsible for their modification (e.g. activation, inhibition or altered sensitivity to intracellular signals) and therefore make a significant impact on intracellular signaling. Maintained calpain activation is known to be associated with disease development and in platelet calpains are involved in both physiological platelet activation as well as pathological platelet hyper-activation.