On the Synthesis of RNA in Lymphocytes Stimulated by Phytohemagglutinin. 1. Induction of Uridine-Kinase and the Conversion of Uridine to UTP

Conversion of uridine to UTP is enhanced in lymphocytes under the influence of phytohemagglutinin concomitant with the induction of uridine kinase. The uridine kinase activity in the induced cells decreases if the cells are treated with antibodies against phytohemagglutinin. The phosphorylation of uridine may be the limiting step in the incorporation of uridine into RNA. Uridine incorporation can thus not be taken as a direct measure of RNA synthesis.