Myosin in developing normal and dystrophic chicken pectoralis. I. Synthesis and degradation.

The synthesis and degradation of pectoralis myosin have been investigated in chickens 15-23 days after hatching. An essentially nonreutilizable tracer amino acid was used to demonstrate differences in the rates of synthesis and degradation of myosin isolated from normal and hypertrophied, cystrophic breast tissue. The analyses have shown that the dystrophic system synthesizes myosin faster than the normal system and that only myosin in dystrophic pectoralis is degraded during the experimental period. Double label experiments have indicated that the heavy chains of dystrophic myosin are destroyed at a rate greater than that characteristic of the light chains.