The binding of nonmuscle caldesmon from brain to microtubules Regulations by Ca2+‐calmodulin and cdc2 kinase

Abstract
Nonmuscle caldesmon from bovine brain bound to microtubules with a stoichiometry of five tubulin dimers to one molecule of caldesmon with values of K A 4.5×105 M−1. The binding of caldesmon to microtubules was inhibited in the presence of Ca2+ and calmodulin. The phosphorylation of caldesmon by cdc2 kinase also eliminated the microtubule-binding activity. These results suggest that caldesmon may play a physiological role in the functions of microtubules.