Genomic structure of the gene encoding cionin--a cholecystokinin/gastrin like peptide

Part of the gene encoding cionin from the protochordate Ciona intestinalis was amplified by polymerase chain reaction from genomic DNA employing synthetic oligonucleotides designed from the reported cDNA sequence. The nucleotide sequence of this gene revealed the presence of two introns of approximately 350 and 57 bp which interrupt the region that encodes pre-pro-cionin. A comparison of the positions of the exon/intron boundaries of the cionin and mammalian gastrin/cholecystokinin genes revealed a different exon/intron pattern. The 5'-donor and 3'-acceptor splice sites found in the cionin gene, however, are in agreement with the mammalian consensus sequence.