The Orct gene of Drosophila melanogaster codes for a putative organic cation transporter with six or 12 transmembrane domains.

Mutations at the lemming (lmg) locus of Drosophila melanogaster cause apoptotic cell death in dividing imaginal cells. Genomic DNA flanking the P element insertion corresponding to the lmg allele lmg03424 has been cloned and found to give rise to multiple transcripts. Several cDNA clones corresponding to this genomic region were isolated and shown to differ due to alternative splicing. The complete nucleotide sequences of two of the longest cDNAs were determined and found to encode proteins with similarity to mammalian organic cation transporter (OCT) proteins. One cDNA potentially encodes a protein with six transmembrane (TM) domains, corresponding to the N-terminal half of a mammalian OCT protein, whereas the other cDNA potentially encodes a protein with 12 TM domains, corresponding to the complete mammalian OCT protein. The gene giving rise to these alternative transcripts has been named Organic cation transporter-like (Orct). The previously identified Acer gene (Taylor, C.A.M., Coates, D., Shirras, A.D., 1996. The Acer gene of Drosophila codes for an angiotensin-converting enzyme homologue. Gene 181, 191 197) appears to lie within an intron of the Orct gene.