A STIMULATION BY CYCLIC 3′,5′-ADENOSINE MONOPHOSPHATE OF AMINO ACID ACTIVATION AND POLYMERIZATION IN RETICULOCYTE HEMOLYSATES

Abstract

With reticulocyte supernatant, cyclic 3',5'-adenosine monophosphate at concentrations of 10(-3) to 10(-2)M causes stimulation of aminoacyl-tRNA synthetases for some, e.g., valine and leucine, but not all, amino acids; it is highest at nonsaturating concentrations of ATP. Similar concentrations of cyclic 3',5'-adenosine monophosphate are found to stimulate phenylalanine polymerization from phenylalanyl transfer ribonucleic acid on polyuridylic acid-charged reticulocyte ribosomes. The degree of stimulation is highest at low GTP concentrations. It is abolished by addition of phosphoenolpyruvate + pyruvate kinase, which stimulate similarly or more effectively at low GTP levels. Under the conditions of these experiments, cyclic 3',5'-adenosine monophosphate did not appreciably inhibit GTP hydrolysis.