Monoclonal antibodies to glutamic acid decarboxylase.

Five monoclonal antibodies that recognize chicken brain glutamic acid decarboxylase (GAD) have been selected and designated GAD-1 to -5. GAD-1 to -5 were selected on the basis of their ability to immunoprecipitate active GAD from crude brain extracts. GAD-1 recognizes an epitope that is conserved in many vertebrates; the epitope recognized by GAD-5 is restricted to the chicken. Radioimmunoassays with GAD-1 indicate that GAD is highly enriched in brain relative to other tissues. GAD was localized immunocytochemically with GAD-1 and GAD-2 in rat cerebellum, spinal cord, and retina. The staining pattern is in agreement with that obtained previously with polyclonal antisera to GAD. GAD from the chicken brain was purified by chromatography on an immunoaffinity column made of GAD-1. NaDodSO4/PAGE analysis of the immunoaffinity-purified GAD fractions shows a major band of 59 kDa and minor bands at 63 and 54 kDa.