Activity of polyribosomes from the muscle of normal and dystrophic mice in cell-free amino-acid incorporation.

Polyribosomes sedimenting in the manner characteristic of those from embryonic chick muscle, as described by Heywood et al. in 1967 (Proc. Natl Acad. Sci. U.S.A. 57,1002--1009) were reproducibly obtained from normal mouse muscle by homogenization of the muscle with a Dounce homogenizer. The polyribosome profiles of dystrophic muscle were qualitatively similar to those of normal muscle except that the relative amount of ribosomes in polyribosome complexes was smaller (44% +/- 3S.E.) in dystrophic muscle than in normal muscle (67% +/- 4S.E.). In spite of this difference, polyribosomes from dystrophic muscle incorporated amino acids in vitro at a faster rate and produced a larger amount of polypeptide at the end of the reaction than polyribosomes from normal muscle.