Characterization of canine pancreas kallikrein cDNA.

Using a combination of primer extension and RT-PCR, the cDNA encoding a canine tissue kallikrein expressed in the pancreas was cloned and sequenced. The cloned 0.85 kbp cDNA contained a complete open reading frame encoding a polypeptide of 261 amino acids. The calculated molecular mass of the processed, unglycosylated, 237 amino acid protein was 26,428 Da. Its mRNA was expressed at high levels in the pancreas, kidney and submaxillary gland. The sequence of the encoded protein was highly homologous with canine prostatic arginine esterase (66%) and human renal/pancreatic kallikrein (74%). Therefore, the cloned cDNA encoded a previously uncharacterized canine kallikrein enzyme which was named dog renal/pancreatic kallikrein or dK2 according to the new nomenclature for kallikrein gene family members. Because of its specific pattern of tissue expression and the presence of all the amino acid residues necessary for kininogenase activity, we suggest that dK2 is the canine true tissue kallikrein.