Discrimination between Messenger Ribonucleic Acids by a Mammalian Translation Initiation Factor

Abstract

A factor from rabbit-reticulocyte ribosome, which stimulates by 5-fold initiation of hemoglobin mRNA translation in Krebs ascites cell extracts, was purified to homogeneity. The factor, a protein of about 65,000 molecular weight in sodium dodecyl sulfate, discriminates between various mRNAs: it stimulates translation of alpha globin mRNA and of tobacco mosaic virus RNA, but has only a small effect on beta globin mRNA and no effect at all on Mengo virus RNA translation.