Regulation of acute and chronic opioid receptor functions by OBCAM, a cell adhesion-like molecule.

Opioid receptors were one of the first class of cell surface receptors to be identified using in vitro binding assays with brain tissue, but for many years efforts to purify and clone them were unsuccessful because of their sensitivity to detergents, their heterogeneity, and the lack of a simple biochemical assay for their function (Loh and Smith 1990). Several laboratories, including the authors’ own, reported purification of opioid-binding proteins (Cho et al. 1986; Gioannini et al. 1985; Maneckjee et al. 1985; Newman and Barnard 1984), but were unable to demonstrate unequivocally that they possessed all the pharmacological properties of in vivo receptors.