ENZYMES FOR DENOVO PYRIMIDINE BIOSYNTHESIS IN DROSOPHILA-MELANOGASTER - THEIR LOCALIZATION, PROPERTIES AND EXPRESSION DURING DEVELOPMENT

1. 1. The first three and last two pyrimidine pathway enzymes are soluble, cytoplasmic activities in Drosophila melanogaster larvae and evidence is presented showing that the last two enzymes comprise a bifunctional enzyme complex. 2. 2. The fourth pathway enzyme, dihydroorotate dehydrogenase, is a particulate activity that co-sediments with mitochondrial cytochrome oxidase. 3. 3. During development, the soluble enzymes exhibit maximal values in embryos and young larvae and show minimal values in later larval stages, pupae and adult males: adult females show high activities due to oocytes and retained embryos. 4. 4. Mutations of the rudimentary locus destroy only the initial three pathway enzymes. © 1979.