Identification and characterization of a Drosophila homologue to the vertebrate neuropeptide cholecystokinin.

Homologues to the cholecystokinin (CCK)-gastrin peptide family have been cloned from Drosophila. The CCK-like precursor found in Drosophila has been designated drosulfakinin (DSK). Genomic and cDNA clones corresponding to the Drosophila neuropeptide precursor encode for three putative peptides. The three peptides (DSK-0, Asn-Gln-Lys-Thr-Met-Ser-Phe-Gly; DSK-I, Phe-Asp-Asp-Tyr-Gly-His-Met-Arg-Phe-Gly; DSK-II, Gly-Gly-Asp-Asp-Gln-Phe-Asp-Asp-Tyr-Gly-His-Met-Arg-Phe-Gly) are flanked by prohormone processing sites and contain C-terminal glycyl residues, a potential amidation site. Two of the peptides, DSK-I and DSK-II, are homologous to CCK-gastrin peptides. Each of the two homologues include a CCK-gastrin-like C-terminal pentapeptide and a conserved sequence corresponding to the sulfated tyrosine in bioactive CCK. The third peptide encoded by the drosulfakinin precursor represents a novel peptide. In situ tissue hybridization indicates the presence of the transcript in the adult head. Chromosomal localization maps the gene to the third chromosome near 81F.