Use of cholate/sodium chloride for solubilisation of brain D2 dopamine receptors

The use of cholate (in the presence of sodium chloride) is described for solubilising brain D2 dopamine receptors. The method described gives in high yield a preparation of solubilised D2 receptors which when assayed by [3H]spiperone binding show little interference from nonspecific and nonstereospecific binding sites. Characterisation by ultrafiltration, electron microscopy, gel filtration, and sucrose density gradient centrifugation has been achieved, showing the receptors to be truly solubilised. Pharmacological characterisation using [3H]spiperone binding suggested the presence of serotonergic S2 receptors in addition to D2 receptors. The pharmacological properties of the solubilised D2 receptors show a good correlation with those of membrane-bound receptors, although ligand binding affinities are lower in the solubilised preparation.