Abstract
Antibodies were raised in rabbits against the βγ subunits of bovine brain GTP-binding proteins, and were purified with a βγ-coupled Sepharose column. Purified antibodies reacted strongly with 36, 000-dalton β subunit and slightly with 35, 000-dalton β and γ subunits, but not with other proteins in an immunoblot assay. Using these purified antibodies, a sensitive enzyme immunoassay method for the quantification of brain βγ was developed. The assay system consisted of polystyrene balls with immobilized antibody F (ab')2 fragments and the same antibody Fab' fragments labeled with β-D-galactosidase from Escherichia coli. The minimum detection limit of the assay was 3 fmol, or 130 pg. Samples from various regions of bovine brain were solubilized with 2% sodium cholate and 1M NaCl, and the concentrations of βγ were determined. The βγ were detected in all the regions, and the highest concentrations were observed in the cerebral cortex and nucleus caudatus. The concentrations of βγ were higher than those of α subunit of GTP-binding protein, Go, in all the regions.
