Glyceraldehyde-3-phosphate dehydrogenase from Drosophila melanogaster. Identification of two isozymic forms encoded by separate genes.

The enzyme glyceraldehyde-3-phosphate dehydrogenase from Drosophila melanogaster has been purified, and these preparations contain two subunits forms which have molecular weights of 37,000 and 35,500, respectively. Each subunit is found in crude extracts, and two activity bands are seen in nondenaturing acrylamide gels. Translation of Drosophila poly(A)-containing RNA results in two products which are precipitable with anti-glyceraldehyde-3-phosphate dehydrogenase serum. Two recombinant DNA clones have been isolated from a genomic library of Drosophila DNA. Each of these clones has the ability to hybrid select mRNAs which translate into both subunit forms. These clones have been genetically characterized by in situ hybridization and restriction mapping. One clone hybridizes to region 13F and the other to region 43E of the Drosophila cytogenetic map. Therefore, it appears that the Drosophila melanogaster genome contains two unlinked genes for glyceraldehyde-3-phosphate dehydrogenase; one of them encodes a protein of 37,000 daltons, the other a protein of 35,500 daltons.