Bifunctional mitochondrial folate-interconverting enzyme that has both NAD/NADP-dependent methylenetetrahydrofolate dehydrogenase and methenyltetrahydrofolate cyclohydrolase activities.
Subcellular locations: Mitochondrion inner membrane
Isoform 1, isoform 4 and isoform 5 are expressed in brain and placenta.