On the genomic organization of the human pancreatic secretory trypsin inhibitor.

Oligonucleotide probes were synthesized according to the published cDNA sequence of human pancreatic secretory trypsin inhibitor (PSTI) and used for the screening of a cosmid library of human genomic DNA. One positive clone was isolated, and a subclone obtained after cleavage with a restriction endonucleae (BamHI) was sequenced. The subcloned fragment contained two exons separated by one intron and parts of the two other introns flanking the exons. The exons are encoding five amino acids of the signal peptide and the subsequent 42 N-terminal amino acids of the human PSTI. The available data allow the conclusion that the arrangement of exons and introns in the human PSTI gene is completely identical to that of the chicken ovomucoid and chicken ovoinhibitor genes.