Purine-resistant Drosophila melanogaster result from mutations in the adenine phosphoribosyltransferase structural gene.

Mutants of Drosophila melanogaster selected for resistance to purine killing are deficient in adenine phosphoribosyltransferase (APRT; E.C. 2.4.2.7) activity. Genetic mapping and complementation analysis demonstrate that purine resistance, deficiency of APRT activity, and differences in the isoelectric point of APRT result from alterations at a single locus, Aprt (map position, 3:3.03). The level of APRT activity shows gene dose dependence in Aprt heterozygotes and in flies that are haploid for different Aprt alleles. Drosophila APRT is a dimer composed of apparently identical 23,000-dalton subunits. These results suggest that Aprt contains the structural gene for APRT.