POLYURIDYLIC ACID STIMULATION OF PHENYLALANINE INCORPORATION IN ANIMAL CELL EXTRACTS

Abstract

Addition of polyuridylic acid (poly U) to a subcellular animal cell system markedly stimulates the incorporation of Cl4-L-phenylalanine into a product insoluble in hot trichloroacetic acid. Polycytidylic, polyadenylic, and polyinosinic acids did not stimulate phenylalanine incorporation. Thus far, no appreciable stimulation by poly U was observed with 13 other amino acids tested. The poly U effect requires the presence of both the microsomal and microsomal supernatant cell fractions. It is dependent upon adenosine triphosphate (ATP) inhibited by ribonuclease (RNAase) and puromycin, and resistant to the action of deoxyribo-nuclease (DNAase). The relevance of these findings to the questions of universality of the genetic code and of the specificity of microsomes in animal cell systems is discussed.