Thiophosphorylation of myosin light chain increases rigor stiffness of rabbit smooth muscle.
1. The effect of thiophosphorylation of the regulatory myosin light chain (MLC20) on rigor stiffness was determined in permeabilized rabbit bladder smooth muscle. 2. Rigor stiffness of alpha-toxin-permeabilized smooth muscle was significantly increased by thiophosphorylation of MLC20. This increase may have been due to partial shortening (melting) in the proximal rod region and/or stiffening of the regulatory domain of the myosin head. 3. We suggest that phosphorylation of MLC20, by increasing the stiffness of the S1 lever arm and/or S2 hinge regions of the myosin molecule, favours separation of the two phosphorylated heads and consequent deinhibition of motor domain activity.
Department of Molecular Physiology and Biological Physics, University of Virginia Health Sciences Center, PO Box 10011, Charlottesville, VA 22906-0011, USA.
A S
AS
Khromov
A V
AV
Somlyo
A P
AP
Somlyo
D000465:Algorithms; D000818:Animals; D004558:Electric Stimulation; D066298:In Vitro Techniques; D016014:Linear Models; D009130:Muscle, Smooth / Q000378:metabolism* / Q000473:pathology; D018994:Myosin Light Chains / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism*; D011817:Rabbits; D012298:Rigor Mortis / Q000378:metabolism* / Q000473:pathology; D001743:Urinary Bladder / Q000378:metabolism / Q000473:pathology
D018994:Myosin Light Chains; D010710:Phosphates; C035638:thiophosphoric acid