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ITPA Pyrophosphatase that hydrolyzes the non-canonical purine nucleotides inosine triphosphate (ITP), deoxyinosine triphosphate (dITP) as well as 2'-deoxy-N-6-hydroxylaminopurine triposphate (dHAPTP) and xanthosine 5'-triphosphate (XTP) to their respective monophosphate derivatives. The enzyme does not distinguish between the deoxy- and ribose forms. Probably excludes non-canonical purines from RNA and DNA precursor pools, thus preventing their incorporation into RNA and DNA and avoiding chromosomal lesions. Defects in ITPA are the cause of inosine triphosphate pyrophosphohydrolase deficiency (ITPAD). It is a common inherited trait characterized by the abnormal accumulation of inosine triphosphate (ITP) in erythrocytes and also leukocytes and fibroblasts. The pathological consequences of ITPA deficiency, if any, are unknown. However, it might have pharmacogenomic implications and be related to increased drug toxicity of purine analog drugs. Three different human populations have been reported with respect to their ITPase activity: high, mean (25% of high) and low activity. The variant Thr-32 is associated with complete loss of enzyme activity, may be by altering the local secondary structure of the protein. Heterozygotes for this polymorphism have 22.5% of the control activity: this is consistent with a dimeric structure of the enzyme. Belongs to the HAM1 NTPase family. 2 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.
Protein type: EC; Hydrolase; Nucleotide Metabolism - purine; Nucleotide Metabolism - pyrimidine; Xenobiotic Metabolism - drug metabolism - other enzymes
Chromosomal Location of Human Ortholog: 20p13
Cellular Component: cytoplasm; cytosol
Molecular Function: identical protein binding; metal ion binding; nucleoside-triphosphate diphosphatase activity; nucleotide binding
Biological Process: chromosome organization and biogenesis; ITP catabolic process; nucleoside triphosphate catabolic process; purine nucleotide catabolic process
Disease: Epileptic Encephalopathy, Early Infantile, 35; Inosine Triphosphatase Deficiency
Reference #:  Q9BY32 (UniProtKB)
Alt. Names/Synonyms: C20orf37; dJ794I6.3; HLC14-06-P; Inosine triphosphatase; inosine triphosphatase (nucleoside triphosphate pyrophosphatase); inosine triphosphatase-A; Inosine triphosphate pyrophosphatase; inosine triphosphate pyrophosphohydrolase; ITPA; ITPase; My049 protein; nucleoside triphosphate diphosphatase; Putative oncogene protein hlc14-06-p
Gene Symbols: ITPA
Molecular weight: 21,446 Da
Basal Isoelectric point: 5.5  Predict pI for various phosphorylation states
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Protein Structure Not Found.
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