Identification of alpha 1-, alpha 2- and alpha 3-subunit isoforms of the GABAA-benzodiazepine receptor in the rat brain.

GABAA receptors purified from the brains of 5- to 10-day-old rats were completely N- and O-deglycosylated using N-glycanase and/or neuraminidase plus O-glycanase. Intact or completely deglycosylated receptors were subjected to SDS-polyacrylamide gel electrophoresis and Western blot analysis. Polyclonal antibodies directed against synthetic aminoacid sequences specific for the GABAA receptor alpha 1-, alpha 2- or alpha 3-subunits each identified an apparently single protein of about 51 kDa, 53 kDa or 59 kDa, respectively, in the intact receptors. In the deglycosylated receptors, however, three different proteins were identified by antibodies directed against the alpha 3-subunit and at least two different proteins were identified by antibodies directed against the alpha 2- or alpha 1-subunit.