THE ISOLATION AND CHARACTERIZATION OF A DROSOPHILA GENE ENCODING A PUTATIVE NAD-DEPENDENT METHYLENETETRAHYDROFOLATE DEHYDROGENASE-METHENYLTETRAHYDROFOLATE CYCLOHYDROLASE

Mammalian NAD-dependent 5,10-methylenetetrahydrofolate dehydrogenase-5 ,10-methenyltetrahydrofolate cyclohydrolase is a bifunctional mitochon drial enzyme expressed in most established cell lines but only in deve loping normal tissues. We report the cloning and molecular characteriz ation of a Drosophila gene (DNMDMC) that encodes a protein with 56% id entity to the mammalian bifunctional protein. Like the mammalian bifun ctional proteins, the Drosophila protein contains a putative mitochond rial targeting sequence and its transcripts are expressed in developin g tissues. Unlike its mammalian homologs, DNMDMC is expressed at high levels in adult tissues. DNMDMC maps to polytene chromosome band 85C, is encoded in three exons, and is closely flanked by two additional ge nes.