7-methylguanosine phosphate-specific 5'-nucleotidase; cytosolic 5'-nucleotidase 3B; cytosolic 5'-nucleotidase III-like protein; cN-III-like protein (NT5C3B, NT5C3L)

Function

• specifically hydrolyzes 7-methylguanosine monophosphate (m(7)GMP) to 7-methylguanosine & inorganic phosphate
• specific activity for m(7)GMP may protect cells against undesired salvage of m(7)GMP & its incorporation into nucleic acids
• also has weak activity for CMP
• UMP & purine nucleotides are poor substrates

7-methylguanosine 5'-phosphate + H2O = a 7-methylguanosine + phosphate

5'-ribonucleotide + H2O = ribonucleoside + phosphate

Kinetic parameters:

• KM=7.8 uM for m(7)GMP
• KM=79 uM for CMP
• KM=355 uM for GMP
• KM=456 uM for AMP
• KM=439 uM for UMP
• Vmax=0.41 umol/min/mg enzyme with m(7)GMP as substrate
• Vmax=12 umol/min/mg enzyme with CMP as substrate
• Vmax=0.13 umol/min/mg enzyme with GMP as substrate
• Vmax=0.07 umol/min/mg enzyme with AMP as substrate
• Vmax=10.7 umol/min/mg enzyme with UMP as substrate
• kcat is 0.24 sec(-1) with m(7)GMP
• kcat is 7 sec(-1) with CMP
• kcat is 0.07 sec(-1) with GMP
• kcat is 0.04 sec(-1) with AMP
• kcat is 6.2 sec(-1) with UMP

Structure

• monomer
• belongs to the pyrimidine 5'-nucleotidase family

Compartment

cytoplasm (putative)

Alternative splicing

named isoforms=2

More general terms

• 5'nucleotidase (5'-ribonucleotide phosphohydrolase)
• phosphotransferase

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=115024
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:115024
• UniProt: http://www.uniprot.org/uniprot/Q969T7.html