stress sensitive B encodes an adenine nucleotide translocase in Drosophilamelanogaster

Adenine nucleotide translocases (ANT) are required for the exchange of ADP and ATP across the inner mitochondrial membrane. They are essential for lif e, and most eukaryotes have at least two different Ant genes. Only one gene had been described from Drosophila, and this had not been characterized ge netically. We show that mutations in this gene correspond to the previously described loci, sesB and l(1)9ED. Immediately adjacent to this gene is ano ther encoding a second ANT protein, which has 78% identity to that encoded by sesB/l(1)9Ed. These two genes are transcribed from a common promoter, an d their mRNAs are produced by differential splicing. Hutter and Karch sugge sted that the sesB ANT gene corresponded to Hmr, a gene identified by an al lele that rescues otherwise inviable interspecific hybrids between Drosophi la melanogaster and its sibling species. This hypothesis is not supported b y our study of the ANT genes of D. melanogaster.