SOME P R A C T I C A L APPLICATIONS OF P R O T E I N SYNTHESIS AND MUSCLE G R O W T H t

Muscle protein biosynthesis activity, assayed in vitro, has been shown to be influenced by several factors including dietary protein quality and quantity, animal age and disease state. Profiles of muscle cytoplasmic extracts were altered when rats were fed diets that varied in protein quality or protein quantity. The isolation and incubation of polyribosomes from muscles of large animals and/or muscle cytoplasmic extract profiling provides tools to assay the synthesis and structure of protein(s) that ultimately may alter the organoleptic quality of the animal protein. Using similar assay systems, the optimum level of dietary protein could be determined that would provide the most efficient production of animal protein. Such systems could also be used to determine the protein nutritional status of animals or humans. An in situ method for the assay of protein synthesis in a small number of homogeneous muscle cells is also proposed.