ATIC
Domain
The IMP cyclohydrolase activity resides in the N-terminal region.
Function
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:10985775, PubMed:11948179, PubMed:9378707). Can use both 10-formyldihydrofolate and 10-formyltetrahydrofolate as the formyl donor in this reaction (PubMed:10985775). Also catalyzes the cyclization of FAICAR to inosine monophosphate (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).
Involvement in disease
AICA-ribosuria due to ATIC deficiency
AICAR
A neurologically devastating inborn error of purine biosynthesis. Patients excrete massive amounts of AICA-riboside in the urine and accumulate AICA-ribotide and its derivatives in erythrocytes and fibroblasts. Clinical features include profound intellectual disability, epilepsy, dysmorphic features and congenital blindness. AICAR inheritance is autosomal recessive.
None
The disease is caused by variants affecting the gene represented in this entry.
Pathway
Purine metabolism; IMP biosynthesis via de novo pathway; 5-formamido-1-(5-phospho-D-ribosyl)imidazole-4-carboxamide from 5-amino-1-(5-phospho-D-ribosyl)imidazole-4-carboxamide (10-formyl THF route): step 1/1.
Purine metabolism; IMP biosynthesis via de novo pathway; IMP from 5-formamido-1-(5-phospho-D-ribosyl)imidazole-4-carboxamide: step 1/1.
Sequence Similarities
Belongs to the PurH family.
Tissue Specificity
Present in the heart, brain, placenta, lung, liver, skeletal muscle, kidney, pancreas.
Cellular localization
- Cytoplasm
- Cytosol
Alternative names
PURH, OK/SW-cl.86, ATIC, Bifunctional purine biosynthesis protein ATIC, AICAR transformylase/inosine monophosphate cyclohydrolase