NT5C3B, also known 7-methylguanosine phosphate-specific 5'-nucleotidase, includes transferase activity and nucleotide binding. Among its related super-pathways are adenosine nucleotides degradation II and Pyrimidine metabolism. Specifically it hydrolyzes 7-methylguanosine monophosphate (m(7)GMP) to 7-methylguanosine and inorganic phosphate. The specific activity for m(7)GMP may protect cells against undesired salvage of m(7)GMP and its incorporation into nucleic acids. Also it has weak activity for CMP. Recombinant human NT5C3B protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography.