The purification and characterization of an inhibitor of protein synthesis from the muscle of dystrophic mice and homozygous control mice

Abstract

Homogenates of hindlimb muscle were obtained from homozygous (+/+) control mice and dystrophic (dy/dy) mice of the ReJ 129 strain and subjected to purification by ion exchange chromatography, gel filtration, centrifugation on sucrose gradients, and sodium dodecyl sulphate gel electrophoresis. A proteinaceous material inhibitory to protein synthesis that was detected previously in fractions from dystrophic muscle (Petryshyn and Nicholls 1978) was present at reduced levels of activity in muscle fractions from homozygous controls. Although the specific activity after the sucrose gradient step was similar in the 2 groups of animals, the activity per animal was 3 times higher in the dystrophic mice. Evidence is presented to support the view that the inhibitory material is identical in the 2 groups and also that the active protein, of an approximate molecular weight of 120 000, can be denatured by heat and 2-mercaptoethanol to the less active form that was described previously, of an approximate molecular weight of 70 000.