Characterization of solubilized human and rat brain beta-endorphin-receptor complex
Abstract
Opioid receptors have been solubilized from human striatal and rat whole-brain membranes by use of 3-(3-cholamidopropyl)dimethylammonio-1-propanesulfonate (CHAPS). Tritiated human beta-endorphin (3H-beta h-EP) binding revealed high-affinity competition by morphine, naloxone, and various beta-EP analogues, suggesting predominantly mu-type binding. Lack of high-affinity competition by (+/-)-3,4-dichloro-N-methyl-N-2-(1-pyrrolidinyl)cyclohexylbenzeneaceta mide methanesulfonate (U50-488, Upjohn) indicated that kappa sites were not labeled by 3H-beta h-EP under these conditions. Affinities were similar in both soluble and membrane preparations except for Metenkephalin, which appears to be rapidly degraded by the solubilized extract. Size differences between human and rat solubilized 3H-beta h-EP-receptor complexes were revealed by exclusion chromatography.