This entry represents a clade of mainly eukaryotic uridine phosphorylases. Uridine phosphorylase (UP) catalyzes the reversible phosphorolysis of uracil ribosides and analogous compounds to their respective nucleobases and ribose 1-phosphate. Human UPP1 has a role in the activation of pyrimidine nucleoside analogues used in chemotherapy, such as 5-fluorouracil [, ]. This subfamily belongs to the nucleoside phosphorylase-I (NP-I) family, whose members accept a range of purine nucleosides as well as the pyrimidine nucleoside uridine. The NP-I family is distinct from nucleoside phosphorylase-II, which belongs to a different structural family.
