In eukaryotes, the enzyme occurs as a trifunctional enzyme that also has methylenetetrahydrofolate dehydrogenase (NADP+) (EC 188.8.131.52) and formate—tetrahydrofolate ligase (EC 184.108.40.206) activity. In some prokaryotes, it occurs as a bifunctional enzyme that also has dehydrogenase (EC 220.127.116.11) activity or formimidoyltetrahydrofolate cyclodeaminase (EC 18.104.22.168) activity.
Rabinowitz, J.C. and Pricer, W.E. The enzymatic synthesis of N10-formyltetrahydrofolic acid and its role in ATP formation during formiminoglycine degradation. J. Am. Chem. Soc.78 (1956) 4176–4178.
Tabor, H. and Wyngarden, L. The enzymatic formation of formiminotetrahydrofolic acid, 5,10-methenyltetrahydrofolic acid, and 10-formyltetrahydrofolic acid in the metabolism of formiminoglutamic acid. J. Biol. Chem.234 (1959) 1830–1849. [PMID: 13672973]