LOCALIZATION OF AN ACTIN-BINDING DOMAIN IN SMOOTH-MUSCLE MYOSIN LIGHT-CHAIN KINASE

Phosphorylation of the regulatory light chain of myosin II by myosin l ight chain kinase is important for regulating many contractile process es. Smooth muscle myosin light chain kinase has been shown to be assoc iated with both actin and myosin filaments in vitro and in vivo. In th is report we define an actin binding region by using molecular deletio ns to generate recombinant mutant proteins that were analyzed by co-se dimentation with F-actin. An actin binding region restricted to residu es 2-42 in the animo terminus of the rabbit smooth muscle myosin light chain kinase was identified.