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 se quenced. The cloned 0.85 kbp cDNA contained a complete open reading fr ame encoding a polypeptide of 261 amino acids. The calculated molecula r 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 highl y homologous with canine prostatic arginine esterase (66%) and human r enal/pancreatic kallikrein (74%). Therefore, the cloned cDNA encoded a previously uncharacterized canine kallikrein enzyme which was named d og renal/pancreatic kallikrein or dK2 according to the new nomenclatur e for kallikrein gene family members. Because of its specific pattern of tissue expression and the presence of all the amino acid residues n ecessary for kininogenase activity, we suggest that dK2 is the canine true tissue kallikrein.