May contribute to UTP accumulation needed for blast transformation and proliferation. ATP + uridine = ADP + H(+) + UMP ATP + cytidine = ADP + CMP + H(+) Pyrimidine metabolism; CTP biosynthesis via salvage pathway; CTP from cytidine: step 1/3. Pyrimidine metabolism; UMP biosynthesis via salvage pathway; UMP from uridine: step 1/1. Interacts with RNF19B. (Microbial infection) Interacts with Epstein-Barr virus/EBV EBNA3. EBNA3 induces isoform 1 translocation to the nucleus, whereas it does change isoform 3 location. Ubiquitous. Ubiquitinated by RNF19B; which induces proteasomal degradation. Belongs to the uridine kinase family.