Abstract
Monoclonal antibodies were prepared to branched-chain amino acid transferase (BAT) type I isozyme purified from rat kidney. Two stable clones producing specific antibodies to the enzyme were obtained. Specificity was confirmed by immunoblots of purified BAT after polyacrylamide gel electrophoresis and testing enzyme inhibition by the antibodies. In the immunohistochemical study, type I BAT was localized in the mitochondria of the proximal tubular cells of the rat kidney. In the liver, reaction was observed in the mitochondria of parenchymal cells. The cells surrounding the central veins exhibited strong immunoreaction. Immunoelectron microscopy using a rapid freezing and substitution technique revealed type I BAT localization in the mitochondria matrices of rat liver parenchymal cell. A faint reaction was present in the cytoplasm. Immunoblot analysis of mitochondrial and post-microsomal fractions from rat liver and kidney also indicated that the enzyme is chiefly present in the mitochondria.
The monoclonal antibodies we prepared may provide a useful tool for studying changes in both isozyme pattern and localization of type I isozyme in the prenatal and neonatal rat and in tumor cells.
