Kinetic characterisation and solubilisation of gamma-hydroxybutyrate receptors from rat brain

The solubilisation of the gamma-hydroxybutyrate (GHB) receptors from rat brain membranes was undertaken as the first step for their molecular characterisation and purification. Treatment of crude brain membranes with high concentrations of NaCl and Triton X-100 resulted in solubilisation of proteins which retain specific GHB binding activity. Ionic detergents do not solubilise and/or inactivate the receptors. Measurements of kinetic parameters of GHB binding showed that the solubilised receptor, in the presence of detergent, exhibited a reduction of affinity for GHB and its endogenous brain analogue trans-4-hydroxycrotonate (T-HCA). The membrane protein extract, submitted to chromatography by gel filtration, showed a single peak of protein with [3H]GHB binding activity. Association and dissociation constants of GHB for its membrane binding site were in accordance with the Kd determined by the Scatchard method.