The voltage dependent anion selective channel family in Drosophila melanogaster.

VDACs (voltage-dependent anion-selective channels) or mitochondrial PORINS are transmembrane proteins forming pores in the outer membrane. In eukaryotic genomes multiple genes coding for VDAC homologues have been discovered, but the functional meaning of this gene redundancy is unknown. In Drosophila melanogasterthree additional genes homologous to the gene porin (CG6647) have been found. As in other occurences, the presence of a gene revealed by genome analysis raises the questions: are these genes really expressed? What are the molecular features of the putative proteins, if they are expressed? Where and when in the organism are they expressed? Consequently have they any specific activity justifying the presence of more isoforms in the organism? To answer to these questions we have produced antibodies against the recombinant proteins corresponding to the whole (VDAC1 and 2) or to substantial portions (VDAC3 and 4) of the known or predicted proteins. Immunohistological and transcriptional analysis has been performed, showing that VDAC2 and 3 are expressed, while VDAC4 was not detected. Structural predictions of VDAC3 are consistent with the presence of additional alpha-helices at the N-terminus of the protein.