Molecular cloning of human gastrin precursor cDNA

We cloned cDNA of gastrin mRNA from human gastric antrum. First we obtained a porcine gastrin precursor cDNA clone using a synthetic oligodeoxyribonucleotide, d(A-A-A-G-T-C-C-A-T-C-C-A-T-C-C-A-T) as a hybridization probe. Then, using this porcine clone as a hybridization probe, human gastrin precursor cDNA clones were obtained. Sequence analysis revealed 4, 303, and 98 nucleotides, respectively, in the 5' untranslated region, in the amino acid coding region, and in the 3' untranslated region. The deduced precursor molecule codes for big and small gastrin, surrounded by pairs of basic amino acids. When the sequences of porcine and human gastrin precursor are compared, a high degree of homology in the active peptide region and lower homology in other regions are observed.