Modulation of recombinant GABA receptor/channel subunits by domain-specific antibodies in Xenopus oocytes

To study interaction of specific antibodies with the GABA receptor/channel, antisera were raised against the extracellular domains of the GABA(A) receptor/channel beta (2) subunit, gamma (2) subunit and the GABA(C) receptor/channel rho (1) subunit, The specificity of the antibodies was characterized by immunocytochemistry and by Western blotting of transfected FDC-P1 cells expressing recombinant GABA receptor/channel subunits. The effects of the antibodies on whole-cell currents in Xenopus laevis oocytes expressing homomeric recombinant GABA receptor/channel beta (2), gamma (2), and rho (1) were studied using two-microelectrode voltage clamp. In the absence of GABA, anti-alpha (2), anti-gamma (2), and anti-pi antisera elicited whole-cell currents in oocytes expressing beta (2), gamma (2), and rho (1) subunits, respectively. The effect of antibody on channel activation was concentration-dependent. The whole-cell currents induced by anti-beta (2) and anti-gamma (2) were several-fold Greater than those induced by application of 100 muM GABA. In Xenopus oocytes expressing recombinant p, subunits, GABA-induced whole-cell currents were inhibited by the anti-p, antibody. In contrast, the GABA-induced whole-cell currents were potentiated severalfold by anti-beta (2) and anti-gamma (2) antibodies in Xenopus oocytes expressing homomeric beta (2) and gamma (2) subunits. Our studies indicate that antibodies specific to the N-terminal domain of GABA receptor/channel subunits can modulate the neurotransmitter receptor function.