Catalyzes the reversible phosphorylytic cleavage of uridine and deoxyuridine to uracil and ribose- or deoxyribose-1-phosphate (PubMed:7744869). The produced molecules are then utilized as carbon and energy sources or in the rescue of pyrimidine bases for nucleotide synthesis. phosphate + uridine = alpha-D-ribose 1-phosphate + uracil Strongly inhibited by 2,2'-anhydro-5-ethyluridine, a competitive inhibitor. Pyrimidine metabolism; UMP biosynthesis via salvage pathway; uracil from uridine (phosphorylase route): step 1/1. Homodimer. By a mixture of inflammatory cytokines: TNF-alpha, IL-1 and interferon gamma. The N-terminus is blocked. Belongs to the PNP/UDP phosphorylase family.