Utilization of Labeled Proteins in Synthesis of Tissue Proteins.

Abstract

Ehrlich ascites cells were incubated in vitro with radioactive amino acids or radioactive ascites proteins prepared biosynthetically. Incubations with free amino acids resulted in accumulation of large amounts of radioactivity in the acid-soluble fraction and in incorporation of radioactivity into the proteins. Incubations with labeled proteins resulted in labeling of cell proteins without significant accumulation of radioactivity in the acid-soluble fraction. Radioactive proteins were isolated from various cell fractions of ascites cells following incubation with labeled free amino acids or proteins. These results suggest that proteins enter ascites cells where they are utilized for synthesis of cellular proteins; free amino acids do not appear to be intermediates in this process.