Increase in Protein Synthetic Activity in Chicken Muscular Dystrophy

Abstract

An increased level of protein synthesis was observed in an in vitro translation when the polyribosomes and postmicrosomal supernatant were prepared from dystrophic rather than normal muscle. This increment in protein synthetic activity was observed even in young dystrophic muscle in which no clinical and morphological abnormalities were detected. No specific increase in the rate of synthesis of any protein could be demonstrated in dystrophic muscle relative to normal muscle. Since a possible reason for the increment in protein synthetic activity was an increase in the activity of factor (s) in the postmicrosomal fraction, several of these were prepared from normal and dystrophic breast muscles and their activities were compared. Crude elongation factor (EF) from dystrophic muscle activated poly (U) directed polyphenylalanine synthesis more than the normal EF. This increase was shown to be due to higher levels of EF1 and EF2 in dystrophic than in normal muscle and not to a decrease in protease or RNase activity in the supernatant of dystrophic muscle relative to normal muscle.
A comparison of the abilities of the postmicrosomal supernatants of normal and dystrophic muscle was made to support protein synthesis in vitro as a function of developmental age. The activity of aminoacyl-tRNA synthetase was also higher in the dystrophic supernatant than in the normal supernatant.