该基因编码一种具有三种不同酶活性的蛋白质：5，10-亚甲基四氢叶酸脱氢酶、5，10-二甲基四氢叶酸环水解酶和10-甲酰四氢叶酸合成酶。这些活性中的每一种都催化四氢叶酸的1-碳衍生物相互转化的三个顺序反应中的一个，这是蛋氨酸、胸苷酸和从头嘌呤合成的底物。三功能酶的活性由两个主要结构域赋予，一个是含有脱氢酶和环水解酶活性的氨基末端部分，另一个是较大的合成酶结构域。[由RefSeq提供，2008年7月]
This gene encodes a protein that possesses three distinct enzymatic activities, 5,10-methylenetetrahydrofolate dehydrogenase, 5,10-methenyltetrahydrofolate cyclohydrolase and 10-formyltetrahydrofolate synthetase. Each of these activities catalyzes one of three sequential reactions in the interconversion of 1-carbon derivatives of tetrahydrofolate, which are substrates for methionine, thymidylate, and de novo purine syntheses. The trifunctional enzymatic activities are conferred by two major domains, an aminoterminal portion containing the dehydrogenase and cyclohydrolase activities and a larger synthetase domain. [provided by RefSeq, Jul 2008]