NORMAL GENOMIC

• Nichols R, Schneuwly SA, Dixon JE
• Identification and characterization of a Drosophila homologue to the vertebrate neuropeptide cholecystokinin.
• J Biol Chem. 1988; 263: 12167-70
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• 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.

• Takahashi Y et al.
• Molecular cloning of the human cholecystokinin gene by use of a synthetic probe containing deoxyinosine.
• Proc Natl Acad Sci U S A. 1985; 82: 1931-5
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• A synthetic DNA based on the known amino acid sequence of the brain/gut peptide cholecystokinin (CCK) was synthesized. This DNA contained deoxyinosines at ambiguous codon positions and was used as a probe to isolate the CCK gene directly from a human genomic library. Nucleotide sequence analysis of the isolated gene revealed that human preprocholecystokinin consists of 115 amino acid residues, with 11 amino acids in common with the human gastrin precursor, another member of the gastrin-CCK family, and that the coding region is separated by a single, long intron. CCK appears to be encoded by a single-copy gene in the haploid human genome, as revealed by genomic Southern hybridization analysis, suggesting that the same gene is expressed both in gut and brain.

• Deschenes RJ, Narayana SV, Argos P, Dixon JE
• Primary structural comparison of the preprohormones cholecystokinin and gastrin.
• FEBS Lett. 1985; 182: 135-8
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• The nucleotide and amino acid sequences of rat preprocholecystokinin and porcine preprogastrin have been aligned and their secondary structures predicted. Both precursors are predicted to be largely in turn and helical configurations. The sequence homology and position of an intron which splits the preprohormones suggest their evolution from a common ancestral protein.

• Anderson JC, Barton MA, Hardy PM, Kenner GW, Preston J, Sheppard RC
• Peptides. XXIV. Syntheses of the N-terminal pentapeptide and C-terminal tetrapeptide sequences of porcine gastrin.
• J Chem Soc [Perkin 1]. 1967; 1: 108-13