Immunochemical Identification of the α1- And α3–Subuntis of the GabaA-Receptor in Rat Brain

Abstract

To identify subunit variants of the GABA_A-receptor antisera were developed against specific cDNA-derived peptide sequences of the α1-and α3–subunits of rat brain. The α1-subunit antiserum selectively recognized a protein of 50±1 kDa in rat and bovine GABA_A – receptor preparations, while the α3–subunit antiserum interacted with a protein doublet of 59±2 kDa and 61±3 kDa. The α-subunit immunoreactivity resides in a large population of GABA_A-receptors as shown by immunoprecipitation of 63+6% of [₃H]flumazenil binding sites with the α1-subunit antiserum. In contrast, only 24±3% of receptor binding sites were precipitated with the α3–subunit antiserum. Co-precipitation studies suggest that the α1- and α3–subunit immunoreactivities do not share the same receptor population while the γ2–subunit immunoreactivity is associated with the α1-subunit immunoreactivity.