NT5C3B - 7-methylguanosine phosphate-specific 5'-nucleotidase - human protein (Function)
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NT5C3B »  7-methylguanosine phosphate-specific 5'-nucleotidase   [ EC ]  (7-methylguanosine nucleotidase)
Protein also known as:  Cytosolic 5'-nucleotidase III-like protein [EC] (cN-III-like protein).
Gene name:  NT5C3B
Entry whose protein(s) existence is based on evidence at protein level
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Specifically 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 has weak activity for CMP. UMP and purine nucleotides are poor substrates.  
  • CuratedUniProtKB
GO molecular function 
5'-nucleotidase activitydefinition[GO:0008253]  
  • IEAEC 2 GO
Magnesium ion bindingdefinition[GO:0000287] silver  
  • IEAInterPro 2 GO
Nucleotide bindingdefinition[GO:0000166]  
  • IEAUniProtKB KW
Protein bindingdefinition[GO:0005515]  
  • IPIIntAct
GO biological process 
Nucleotide metabolic processdefinition[GO:0009117]  
  • IEAUniProtKB KW
Enzymatic activity 
This protein acts as an enzyme. It is known to catalyze the following reactions
N(7)-methyl-GMP + H(2)O N(7)-methyl-guanosine + phosphate.  
  • CuratedUniProtKB
CMP + H(2)O cytidine + phosphate.  
  • CuratedUniProtKB
EC A 5'-ribonucleotide + H(2)O a ribonucleoside + phosphate.  
  • CuratedUniProtKB

Biophysicochemical properties

Kinetic parameters
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.
KM 456 uM for AMP
KM 355 uM for GMP
KM 439 uM for UMP
KM 79 uM for CMP
KM 7.8 uM for m(7)GMP
Vmax 0.07 umol/min/mg enzyme with AMP as substrate
Vmax 0.13 umol/min/mg enzyme with GMP as substrate
Vmax 0.41 umol/min/mg enzyme with m(7)GMP as substrate
Vmax 10.7 umol/min/mg enzyme with UMP as substrate
Vmax 12 umol/min/mg enzyme with CMP as substrate


Biological process 
Nucleotide metabolism  definition   [KW-0546]
Molecular function 
Hydrolase  definition   [KW-0378]
Technical term 
Reference proteome  definition   [KW-1185]

Further external links

GenomeRNAi: 115024
PRO: PR:Q969T7