APStracts 2:0209C, 1995.

Smooth muscle contractility is modulated by myosin tail -s2-lmm hinge region interaction. Cai, Shuang, Donald G. Ferguson, Anne F. Martin, and Richard J. Paul. Department of Physiology and Biophysics and Pharmacology and Cell Biophysics, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0576, USA

APStracts 2:0209C, 1995.

The functional significance of two major smooth muscle myosin isoforms, which differ in the non-enzymic, C-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-LMM hinge region of myosin using SDS 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.

Received 15 February 1994; accepted in final form 15 May 1995.
APS Manuscript Number C85-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 May 1995.