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Smooth muscle contractility is modulated by myosin tail-S2-LMM hinge region interaction

1995; American Physical Society; Volume: 269; Issue: 5 Linguagem: Inglês

10.1152/ajpcell.1995.269.5.c1126

1522-1563

Sheng F. Cai, Donald G. Ferguson, Alberto Martı́n, R. J. Paul,

Cardiovascular Effects of Exercise

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.