has participant poly(nucleoside 5'-monophosphate) polyanion poly(RNA)-3'-uridine ribonucleotide polyanion diphosphate(3-) UTP(4-) RNA uridylyltransferase activity RHEA:14785 terminal uridylyltransferase activity Catalysis of the reaction: UTP + RNA(n) = diphosphate + RNA(n+1). MetaCyc:RNA-URIDYLYLTRANSFERASE-RXN EC:2.7.7.52 polynucleotide uridylyltransferase activity Reactome:R-HSA-8941312 GO:0050265 UTP:RNA uridylyltransferase activity poly(U) polymerase activity molecular_function TUT activity uridylyltransferase activity catalytic activity, acting on RNA