Calmodulin bridging of IQ motifs in myosin‐V

Abstract
Ca2+‐saturated calmodulin binds to double‐length IQ lever‐arm sequences from murine myosin‐V, forming a 1:1 “bridging” complex with very high affinity, (K d2+‐dependent CaM dissociation from the IQ‐region. Structural considerations suggest that formation of the 1:1 complex requires a severe distortion of the lever‐arm, potentially regulating functional motility. This would be consistent with a recent report of diverse, irregular shapes of the lever arm of myosin‐V induced by the presence of Ca2+.