title: Smooth muscle contractility is modulated by myosin tail-S2-LMM hinge region interaction.
abstract: The functional significance of two major smooth muscle myosin isoforms, which differ in the nonenzymic COOH-terminal tail region, is not known. We report here that a 13-amino acid peptide, which mimics a region of the tail unique to the SM1 myosin isoform, inhibits contraction velocity in permeabilized smooth muscle. This peptide is shown to bind to the S2-light meromyosin (LMM) hinge region of myosin using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, photoaffinity labeling, and immunoelectron microscopy. Our results suggest that novel intermolecular contacts between the tail and S2-LMM hinge regions of adjacent myosin molecules in the thick filament may modulate contractility and provide a basis for distinct isoform function.
mesh_terms: D000818:Animals; D015153:Blotting, Western; D006168:Guinea Pigs; D008854:Microscopy, Electron; D008958:Models, Molecular; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000502:physiology*; D009218:Myosins / Q000737:chemistry* / Q000502:physiology* / Q000648:ultrastructure
chemical_list: D009218:Myosins