MLCK moves on Actin Filament and Stress Fiber of Smooth Muscle Cells

Abstract

We are interested in the mechanism of phosphorylation of smooth muscle myosin (SMM) by the myosin light chain kinase -calmodulin-Ca2+ complex (MLCK-CaM-Ca2+). This reaction is required for activation of SMM catalytic activity and smooth muscle contraction. In previous studies we characterized tightly-bound SMM-MLCK-CaM complexes in an in vitro model system and demonstrated that SMM-MLCK-CaM complexes co-purified from smooth muscle were functional, i.e. MLCK was able to phosphorylate SMM and the phosphorylated SMM resulted in actin filament motility in an in vitro assay.