Isolation of a genomic clone for bovine pancreatic trypsin inhibitor by using a unique-sequence synthetic DNA probe

Unique-sequence synthetic DNA probes, based on the known amino acid sequence of bovine pancreatic trypsin inhibitor, were constructed from oligodeoxynucleotides. In genomic Southern blot experiments, these probes were shown to hybridize specifically to discrete restriction fragments. A synthetic probe also was used to isolate a cloned BPTI gene from a bovine genomic library. DNA sequence analysis of this clone indicated that the BPTI coding region was neither preceded by a start codon nor immediately followed by a termination codon. This suggests that the mature form of BPTI may be produced through proteolytic processing from a larger polypeptide precursor.