Bifunctional purine biosynthesis protein PURH - P31939 (PUR9_HUMAN)


Protein Feature View of PDB entries mapped to a UniProtKB sequence  

Bifunctional enzyme that catalyzes the last two steps of purine biosynthesis (PubMed:11948179, PubMed:14756554). Acts as a transformylase that incorporates a formyl group to the AMP analog AICAR (5-amino-1-(5-phospho-beta-D-ribosyl)imidazole-4-carboxamide) to produce the intermediate formyl-AICAR (FAICAR) (PubMed:9378707, PubMed:11948179, PubMed:10985775). Can use both 10-formyldihydrofolate and 10-formyltetrahydrofolate as the formyl donor in this reaction (PubMed:10985775). Also catalyzes the cyclization of FAICAR to IMP (PubMed:11948179, PubMed:14756554). Is able to convert thio-AICAR to 6-mercaptopurine ribonucleotide, an inhibitor of purine biosynthesis used in the treatment of human leukemias (PubMed:10985775). Promotes insulin receptor/INSR autophosphorylation and is involved in INSR internalization (PubMed:25687571). UniProt
Catalytic Activity
10-formyldihydrofolate + 5-amino-1-5-phospho-D-ribosylimidazole-4-thiocarboxamide = 6-thio-IMP + 7,8-dihydrofolate + H2O UniProt
Pathway Maps
      ESCHER  BiGG
Subunit Structure
Homodimer (PubMed:14756553, PubMed:14966129). Associates with internalized INSR complexes on Golgi/endosomal membranes (PubMed:25687571). Interacts with INSR; ATIC together with PRKAA2/AMPK2 and HACD3/PTPLAD1 is proposed to be part of a signaling network regulating INSR autophosphorylation and endocytosis (PubMed:25687571). UniProt
The IMP cyclohydrolase activity resides in the N-terminal region. UniProt
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