[Solubilization and various properties of NAD-binding receptor protein from rat brain synaptic membranes]

The NAD-binding receptor protein has been solubilized from the synaptic membranes of the rat brain by different detergents. Digitanin proved to be the most effective detergent which exerted no action on the specific binding of [14C]NAD with the solubilized receptor protein. Kinetic parameters of the soluble ligand-receptor complex were studied. The affinity of the solubilized receptor protein to NAD did not change as compared to the protein of native membranes. The specific binding of [14C]NAD was saturated at Kd = 0.53 microM, Bmax = 0.011 nmol per 1 mg of protein. The molecular weight of the soluble NAD-receptor complex determined under native conditions was equal to 115 kDa.