Studies on Amino Acyl Transfer from Soluble-RNA to Rat Liver Ribonucleo-protein Particles; Effect of Soluble and Microsomal Extracts^*

Studies on Polynucleotide-Stimulated Amino Acyl Transfer From Soluble-Rna to Rat Liver Ribosomes

“…Results and Discussion.-Previous studies demonstrated the requirements for GTP and a soluble fraction of the cell for amino acyl transfer to cytoplasmic ribonucleoprotein particles.22 23 Recent reports from this laboratory23' 28 have presented evidence indicating the presence of two activities essential for amino acyl transfer. One of these, transferase I, catalyzes amino acyl transfer to intact microsomes, but is inactive in experiments with purified ribosomes.…”

“…This study was initiated since it appeared of considerable importance to determine whether comparable evidence could be obtained in mammalian cells. The use of a highly purified rat liver system, available in this laboratory,22' 23 that catalyzes the transfer of amino acids from amino acyl s-RNA to ribosomal protein was considered since it is relatively free of interfering reactions which are also involved in protein synthesis. The amino acyl transfer reaction represents an isolated reaction, dissociated from amino acid activation and the synthesis of s-RNA amino acid, which leads to the incorporation of amino acids into proteins.…”

“…[24][25][26][27] Materials and Methods. The preparation of amino acyl s-RNA labeled with C14-amino acids, deoxycholate-extracted ribosomes, pH 5 supernatant, and two purified soluble protein factors, designated amino acyl transferases (or polymerases) I and II, from rat liver has been described previously.22' 23 The resolution of transferases I and II from the pH 5 supernatant fraction and the purification of transferase II, which has also been obtained from microsomal extracts,23' 28 will be described in detail in a subsequent communication. Polyuridylic acid (poly U), polycytidylic acid (poly C), polyuridylic-guanylic acid (poly UG, 5:1), polyuridylic-cytidylic acid (poly UC, 5:1).…”