title: [Effect of phosphorylating myosin light chains and ionic strength on actin-myosin interaction in a relaxed skeletal muscle fiber].
abstract: The effect of LC-2 phosphorylation and ionic strength on actin-myosin interaction in relaxed skeletal muscle fibers have been studied using polarization fluorimetry. F-actin was chemically modified by the fluorescent dye, rhodamine-phalloidin, and the mode of myosin-actin interaction was estimated by a polarized fluorescence technique based on changes in the dye orientation (phi E) and thin filament flexibility (sin 2 theta). Phosphorylation of LC-2 at relaxation in low ionic strength induced typical for the force production ("strong" binding) state changes in the polarized fluorescence of F-actin (decreasing of phi E and increasing of sin 2 theta). In contrast, phosphorylation in high ionic strength induced changes similar to those typical for the nonforce production ("weak" binding) state (phi E did not change, while sin 2 theta decreased). It is suggested that phosphorylation of LC-2 at approximately physiological ionic strength may provide fiber relaxation by switching some of the cross-bridges to the nonforce production state at the initial stage of relaxation.
authors.forename: N N
authors.initials: NN
authors.lastname: Efimov
authors.forename: Iu S
authors.initials: IuS
authors.lastname: Borovikov
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D005454:Fluorescence Polarization; D009126:Muscle Relaxation; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology; D018994:Myosin Light Chains / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D009994:Osmolar Concentration; D010766:Phosphorylation; D011817:Rabbits
chemical_list: D000199:Actins; D018994:Myosin Light Chains; D009218:Myosins