159] Description of nucleic acid coding for mammalian protein synthesis

Abstract

By testing the coding potential of various synthetic RNA's in a given mammalian system and comparing the results to those obtained with the Escherichia coli system, information relating to the question of universality of the code can be obtained. The use of synthetic messenger RNA's (mRNAs) in mammalian systems can also provide information regarding the mechanism of interaction between mRNA and ribosomes and the specificity of mammalian ribosomes in protein synthesis. As supplementation of mammalian extracts with synthetic mRNA's greatly enhances the overall rate of protein synthesis, these systems are generally useful for studying the mechanism of polypeptide synthesis. The subeellular systems obtained from mammalian cells require a considerably higher concentration of synthetic mRNA's for maximal activity than comparable reactions in the Escherichia coli system. Even under optimal conditions, the mammalian systems are considerably less active than the Escherichia coli system. The activity is sufficiently high to indicate the types of nucleotides required to code for a given amino acid.