Species Specificity of Amino Acid Transfer-RNA and Amino Acyl T-RNA Synthetase

The amino acyl-transfer RNA formation represents the first stage in protein synthesis at which discrimination between amino acids takes place. It is a specific one in the sense that each amino acid is bound to a particular RNA. Several observations indicate that this first stage in protein synthesis depends on the source of both the transfer RNA (T-RNA) and the amino acyl-T-RNA synthetase. Thus, valyl-T-RNA synthetase from E. coli had a low activity for forming valyl-T-RNA with T-RNA of yeast, Azotobacter vinelandii, Turnip Yellow Mosaic Virus, TMV, and rat liver (Berg and Ofengand, 1958). Guinea pig liver enzymes could not esterify leucine onto E. coli T-RNA, although RNA preparations from a number of mammalian sources were approximately equivalent (Allen et al., 1960). Similar observations have been reported (Rendi and Ochoa, 1961). A more detailed study has shown that the various degrees of interchangeability of the amino acyl-T-RNA synthetase and T-RNA...