title: Bundling of actin filaments by myosin light chain kinase from smooth muscle.
abstract: Myosin light chain kinase has an inhibitory effect on the interaction of actin filaments with phosphorylated smooth muscle myosin. Myosin light chain kinase binds to actin filaments, and the inhibition is attributable to the actin-binding activity and not the kinase activity of myosin light chain kinase [Kohama et al. (1992) Biochem. Biophys. Res. Commun. 184, 1204-1211]. We now report that myosin light chain kinase is able to assemble actin filaments into thick bundles, which can be visualized by optical and electron microscopy and can be monitored by measuring the sedimentation and flow birefringence of actin filaments. The bundling activity of myosin light chain kinase is abolished by calmodulin in the presence of Ca2+. The possibility is discussed that myosin light chain kinase has multiple actin-binding sites through which it can cross-link actin filaments.
authors.affiliation: Department of Pharmacology, Gunma University School of Medicine, Maebashi, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Hayakawa
authors.forename: T
authors.initials: T
authors.lastname: Okagaki
authors.forename: S
authors.initials: S
authors.lastname: Higashi-Fujime
authors.forename: K
authors.initials: K
authors.lastname: Kohama
mesh_terms: D000199:Actins / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D001718:Birefringence; D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000494:pharmacology; D002645:Chickens; D004533:Egtazic Acid / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D005895:Gizzard, Avian; D008854:Microscopy, Electron; D008970:Molecular Weight; D009130:Muscle, Smooth / Q000201:enzymology*; D009132:Muscles / Q000378:metabolism*; D009219:Myosin-Light-Chain Kinase / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D000199:Actins; D002147:Calmodulin; D004533:Egtazic Acid; D009219:Myosin-Light-Chain Kinase; D002118:Calcium