Myosin Heavy and Light Chains and Myosin Light Chain Kinase in Skeletal and Smooth Muscle of Some Wild Avian Species

Abstract

Electrophoretic and enzymatic techniques were used to study the myosin present in skeletal muscle (pectoralis muscle) of chicken and eight wild avian species (moorhen, redwing, blackbird, fieldfare, starling, jay, green woodpecker, woodcock). All avian pectoralis muscles are composed of only fast-type myosin. Three light chains, LC1F, LC2F and LC3F, were observed for all myosins. LC1F was characterized by a major electrophoretic mobility in woodcock and jay. LC2F and LC3F appear to have the same electrophoretic mobilities in all species studied. The mean value of the LC3F/LC2f ratio was lower in wild avian myosin than in chicken. Only one type of myosin heavy chain was detected, except for woodcock in which a doublet was observed. Myosin ATPase activity was higher for wild species as compared to chicken. Taken together, these results indicate that myosin present in wild avian species is of fast-red type, a structural characteristic that generates the rapid output of power required for a rapid take-off and continuous sustained flight. Immunological techniques revealed that gizzard smooth muscle of four wild avian species (moorhen, jay, starling, green woodpecker) contained one type only of myosin light chain kinase (MLCK), which cross-reacted with polyclonal antibody against chicken MLCK and was characterized by the same electrophoretic mobility as that present in the chicken.