On the mechanism of calmodulin-induced inhibition of microtubule assembly in vitro.
Binding of calmodulin to microtubule-associated proteins (MAPs) was analyzed by the equilibrium gel filtration method. The apparent dissociation constant (Kd) of calmodulin binding was found to be 2 microM for tau, and 5 microM for MAP2. These Kd values were similar to the Kd previously determined for calmodulin binding to tubulin. The inhibitory effect of increasing concentrations of calmodulin on the kinetics of microtubule assembly from tau and tubulin was not mimicked by decreasing the concentration of tau alone or tubulin alone. These results suggest that calmodulin inhibits microtubule assembly by its binding to both MAPs and tubulin.
D000818:Animals; D001921:Brain / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism / Q000494:pharmacology*; D066298:In Vitro Techniques; D007700:Kinetics; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008870:Microtubules / Q000187:drug effects* / Q000378:metabolism; D013552:Swine; D014404:Tubulin / Q000378:metabolism; D016875:tau Proteins
D002147:Calmodulin; D008869:Microtubule-Associated Proteins; D014404:Tubulin; D016875:tau Proteins