PT - JOURNAL ARTICLE AU - R M Denney AU - R R Fritz AU - N T Patel AU - S G Widen AU - C W Abell TI - Use of a monoclonal antibody for comparative studies of monoamine oxidase B in mitochondrial extracts of human brain and peripheral tissues. DP - 1983 Jul 01 TA - Molecular Pharmacology PG - 60--68 VI - 24 IP - 1 4099 - http://molpharm.aspetjournals.org/content/24/1/60.short 4100 - http://molpharm.aspetjournals.org/content/24/1/60.full SO - Mol Pharmacol1983 Jul 01; 24 AB - Monoamine oxidase B (MAO B; EC 1.4.3.4) activity in detergent extracts of mitochondria from autopsy brain (gray matter and medulla), liver, lung, and kidney from a single individual and from pooled, human platelets could be immunoprecipitated by a monoclonal anti-human platelet MAO B antibody (MAO-1C2) in combination with appropriate secondary reagents. MAO A activity, which was detected in brain, liver, lung, and kidney, was not immunoprecipitated under the same conditions. All MAO B-containing extracts, regardless of tissue source, inhibited immunoprecipitation of [3H]pargyline-labeled human platelet MAO, and the shapes of the inhibition curves were identical. The concentration of immunologically detectable MAO B protein in the extracts was estimated from immunoprecipitation competition data by reference to a standard curve relating observed inhibition of immunoprecipitation to the concentration of catalytically active platelet MAO added (estimated from [3H]pargyline binding data). MAO B protein concentrations measured by this radioimmunoassay were similar to concentrations of active MAO B as measured by pargyline binding. These results demonstrate that in the brain and peripheral tissues studied, molecules with MAO B activity share a unique antigenic determinant and similar catalytic efficiency. They also extend previous observations that MAO B molecules extracted from mitochondria bear an antigenic determinant which is not present on MAO A molecules. These results demonstrate the validity of a new competitive radioimmunoassay for active plus inactive MAO B concentration in human platelet extracts and extracts of mitochondria from human tissues. This radioimmunoassay should complement [3H]pargyline binding assays and enzyme activity assays in studies designed to clarify the mechanisms of genetic, disease, and treatment factors which lead to differences in MAO B function among individuals.