title: Origin of alpha-glycerophosphate dehydrogenase isozymes in Drosophila melanogaster and their functional relationship in the alpha-glycerophosphate cycle.
abstract: The basis for the differentiation of L-glycerol-3-phosphate dehydrogenase (alpha-GPDH) into larval and adult isozymes in Drosophila melanogaster was investigated by the correlation of a lack of appearance of each isozyme during development within Drosophila bearing alpha-GPDH "null" alleles and by the study of a putative conversion factor. Conversion studies indicate the presence of a heat-labile RNase-resistant conversion factor present in crude larval extracts with the ability to convert GPDH-1 to GPDH-2 and GPDH-3 but not vice versa. In addition, "null" mutations at the Gpdh locus obliterate all isozymatic species of alpha-GPDH in all developmental stages. These observations suggest that all alpha-GPDH isozymes are the product of a single structural gene and that the multiple forms of this enzyme arise during successive developmental stages through an epigenetic modification of the primary Gpdh+ polypeptide. Finally, observations are reported which bear on the functional divergence of the alpha-glycerophosphate cycle in the adult and larval stage of development.
mesh_terms: D000483:Alleles; D000818:Animals; D002875:Chromosomes; D003433:Crosses, Genetic; D004331:Drosophila melanogaster / Q000201:enzymology; D005260:Female; D005796:Genes; D005993:Glycerolphosphate Dehydrogenase / Q000378:metabolism; D005994:Glycerophosphates / Q000378:metabolism*; D006579:Heterozygote; D007527:Isoenzymes / Q000378:metabolism; D007814:Larva / Q000201:enzymology; D008297:Male; D008675:Metamorphosis, Biological
chemical_list: D005994:Glycerophosphates; D007527:Isoenzymes; D005993:Glycerolphosphate Dehydrogenase