uridine phosphorylases similar to a human UPP1 and UPP2
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-1 family includes phosphorolytic nucleosidases, such as purine nucleoside phosphorylase (PNPs, EC. 2.4.2.1), uridine phosphorylase (UP, EC 2.4.2.3), and 5'-deoxy-5'-methylthioadenosine phosphorylase (MTAP, EC 2.4.2.28), and hydrolytic nucleosidases, such as AMP nucleosidase (AMN, EC 3.2.2.4), and 5'-methylthioadenosine/S-adenosylhomocysteine (MTA/SAH) nucleosidase (MTAN, EC 3.2.2.16). The NP-I family is distinct from nucleoside phosphorylase-II, which belongs to a different structural family.
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