5"-Nucleotidase, Cytosolic III (NT5C3)

Pyrimidine 5-prime-nucleotidase (P5N), also called uridine 5-prime monophosphate hydrolase (UMPH), catalyzes the dephosphorylation of the pyrimidine 5-prime monophosphates UMP and CMP to the corresponding nucleosides. There are 2 isozymes of pyrimidine 5-prime nucleotidase in red blood cells, referred to as type I (UMPH1) and type II (UMPH2). The 2 enzymes are not separable by electrophoresis in humans but have distinct kinetic properties, and the proteins show no homology. Cloning of UMPH1 and expression in E. coli demonstrated that the protein consists of 286 amino acids and is identical to a previously identified lupus inclusion protein, p36. Marinaki et al.determined that alternative splicing of exon 2 results in a 297-amino acid form of the protein.