A monoclonal antibody specific for the Yc subunit of rat liver glutathione S-transferase B.

A monoclonal antibody against rat liver glutathione S-transferase B, which consists of subunits Ya (Mr 27,000) and Yc (Mr 29,500), was produced in a mouse hybridoma system. The monoclonal antibody, BE6Yc1, was of the immunoglobulin G1 class and specifically recognized glutathione S-transferase B showing no cross-reactivity against the dimeric form of Ya, ligandin, in enzyme-linked immunosorbent assay. A glutathione S-transferase B-BE6Yc1 monoclonal antibody complex was identified from the zymogram pattern on starch gel electrophoresis. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis of rat liver glutathione S-transferase B, followed by Western blotting with BE6Yc1 antibody, a single polypeptide with a molecular weight of 29,500, identical to the Yc subunit of rat liver glutathione S-transferase B, was identified. The antibody showed no cross-reactivity with the Ya subunit with a molecular weight of 27,000 of either glutathione S-transferase B or ligandin. These results show that there are at least two distinct epitopes in the Ya and the Yc subunit. The monoclonal antibody did not block the catalytic activity of glutathione S-transferase B toward cumene hydroperoxide and possibly also 1-chloro-2,4-dinitrobenzene. Quantitative differences in expression of the Yc subunit of glutathione S-transferases were demonstrated in extracts of various normal tissues with the BE6Yc1 antibody by Western blot analysis. The Yc subunit was found to be present at much lower levels in kidney, small intestine, spleen, and lung than in liver and testis.