Identification and expression of kallikrein gene family in rat submandibular and prostate glands using monoclonal antibodies as specific probes.

Panels of monoclonal antibodies to three vasoactive peptide-producing enzymes: tissue kallikrein, tonin and arginine esterase A were developed, characterized and used as probes for identification of tissue-specific expression. In addition, immunoblot analyses were performed, using monospecific monoclonal antibodies which did not show cross-reactivity to related-purified enzymes in enzyme-linked immunosorbant assay (ELISA), and radioimmunoassay. We obtained the following results. In rat submandibular gland extract, the expression of 38 kDa kallikrein, 32 kDa tonin, and 18 kDa heavy chain of esterase A was identified by monoclonal antibodies to kallikrein (V4D11), tonin (1F11), and esterase A (5A10, 6C11, and 4B12), respectively. In the prostate gland, a 32 kDa kallikrein-like protein was identified by monoclonal antibodies to esterase A (5A10, 6C11 and 4B12) and by antibodies recognizing both tonin and esterase A (5A5), but not by antibody to kallikrein (V4D11) or to tonin (1F11, 1G6) in Western blot analysis. The esterase A-like enzyme in the prostate gland was found within the cytoplasm of ductal epithelial cells by using monoclonal anti-esterase A antibody (5A10) but not by employing anti-tonin antibody (1F11). These results indicate that tissue kallikrein, tonin, and esterase A are all expressed in the submandibular gland, while only esterase A or an esterase A-like enzyme is expressed in the prostate gland. The specific monoclonal antibodies can be used as probes for the identification and expression of the kallikrein gene-family enzymes.