Translation of myosin heavy chain messenger ribonucleic acid in an eukaryotic initiation factor 3- and messenger-dependent muscle cell-free system.

A cell-free protein synthesis system has been prepared from embryonic chick muscle; this system is dependent on initiation factor eukaryotic initiation factor 3 (eIF-3) and mRNA for efficient translation. Highly purified chick muscle eIF-3 has been fractionated into "core" and discriminatory components. In the presence of core eIF-3 from chick muscle or rabbit reticulocytes, myosin heavy chain mRNA is translated less efficiently than globin mRNA present in an equimolar concentration. When the discriminatory components are added to core eIF-3 from either source, myosin mRNA is translated with a greater efficiency. Thus, chick muscle eIF-3 contains components which allow it to recognize and stimulate specifically the translation of myosin mRNA in a muscle cell-free protein synthesis system.