title: Characterization and partial purification of solubilized active opiate receptors from toad brain.
abstract: Opiate receptors have been solubilized from toad brain membranes in active form by using digitonin. Between 40% and 50% of the stereospecific binding activity present in toad brain membranes is recoverable in the ultracentrifugal supernatant of digitonin extracts. Binding of opiates to the solubilized receptor is enhanced 4- to 5-fold by decreasing digitonin concentration to 0.1% or less prior to binding. The solubilized receptor is similar to the membrane-bound receptor in its affinity for various ligands and its sensitivity to heat, trypsin, and N-ethylmaleimide. Moreover, the sodium effect seen in membrane-bound receptor is retained in the solubilized preparation. Both membrane-bound and soluble toad receptors show weak binding of enkephalins, suggesting that they are predominantly of the mu type. The solubilized opiate receptor has an approximate molecular weight of 350,000-400,000. Purification of up to 20-fold has been achieved by gel filtration on Sepharose CL-6B.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D001923:Brain Chemistry; D002024:Bufo marinus; D002462:Cell Membrane / Q000378:metabolism; D003902:Detergents; D004174:Diprenorphine / Q000378:metabolism; D007700:Kinetics; D011957:Receptors, Opioid / Q000302:isolation & purification* / Q000378:metabolism; D012995:Solubility; D013329:Structure-Activity Relationship
chemical_list: D003902:Detergents; D011957:Receptors, Opioid; D004174:Diprenorphine