D₁ and D₂ Dopamine Receptors: Identification by Photoaffinity Labeling and Purification by Affinity Chromatography

Abstract

In an attempt to characterize the receptors which mediate the physiological actions of dopamine, we have developed several probes for the characterization of both the D₁ and D₂ subtypes of dopamine receptors. To identify the ligand binding site of these receptors we have developed affinity and photoaffinity probes based on the structure of high affinity selective antagonists. [¹²⁵I]p(azidcphenethyl) spiperone has been used to identify the ligand binding site of the D₂ dopamine receptor in several tissues (Amlaiky and Caron, 1985). More recently, our laboratory has also characterized the ligand binding subunit of the D₁ dopamine by covalently incorporating a radioiodinated arylamine derivative of the selective D₁ antagonist SCH-23390 into rat striatal membranes by photoaffinity crosslinking (Amlaiky et al. 1987). Another derivative of the potent D₂ antagonist spiperone (carboxynethyleneoximinospiperone) has been used in the development of an affinity chromatography procedure for the purification of the D₂ receptor from bovine anterior pituitary gland (Senogles et al., 1986).