GABAA receptor alpha1 and alpha6 subunits mediate cell surface anchoring in cultured cells

The clustering and immobility of gamma-aminobutyric acid type A receptors (GABAARs) at discrete and functionally significant domains on the nerve cell surface is an important determinant in the integration of synaptic inputs. To investigate the role that different GABAAR alpha subunit isoforms play in determining receptor mobility, alphaxbeta3gamma2s subunits (where x = subunit isoforms 1-6) were co-transfected into COS 7 and human embryonic kidney (HEK) 293 cells and the surface mobility of these recombinant complexes was measured by fluorescence photobleach recovery (FPR). In addition, the lateral mobility of endogenous GABAARs in cerebellar granule (CG) cells was measured. We show that the alpha1 and alpha6 subunits immobilize recombinant GABAAR in transfected cells. This is consistent with the immobility of native receptors in CG cells, which express alpha1 and alpha6.