Calmodulin: a prototypical calcium sensor

Abstract

Calmodulin is the best studied and prototypical example of the E–F-hand family of Ca²⁺-sensing proteins. Changes in intracellular Ca²⁺ concentration regulate calmodulin in three distinct ways. First, at the cellular level, by directing its subcellular distribution. Second, at the molecular level, by promoting different modes of association with many target proteins. Third, by directing a variety of conformational states in calmodulin that result in target-specific activation. The calmodulin-dependent regulation of protein kinases illustrates the potential mechanisms by which Ca²⁺-sensing proteins can recognize and generate affinity and specificity for effectors in a Ca²⁺-dependent manner.