Characterization of solubilized opiate receptors from human placenta.
A solubilized opiate receptor from human placental membranes binds [3H]etorphine saturably, reversibly, and stereospecifically. The binding activity is shown to be truly soluble because it migrates between two soluble proteins on Sepharose CL-6B. The solubilized macromolecular complex behaves as a molecule with an apparent Stokes radius of 70 A and contains a protein as an essential constituent. The solubilized receptors bind [3H]ethylketocyclazocine with high affinity in a saturable and stereospecific manner. Naloxone inhibits [3H]etorphine and [3H]ethylketocyclazocine binding to the solubilized receptor. Sodium inhibits [3H]etorphine but not [3H]naloxone binding. These observations indicate that the solubilized receptor from human placental membranes is active and retains properties of membrane-bound receptors.
D001667:Binding, Competitive; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003496:Cyclazocine / Q000031:analogs & derivatives / Q000378:metabolism; D016314:Ethylketocyclazocine; D005048:Etorphine / Q000378:metabolism; D005260:Female; D006801:Humans; D009270:Naloxone / Q000378:metabolism; D010920:Placenta / Q000032:analysis*; D011247:Pregnancy; D011957:Receptors, Opioid / Q000302:isolation & purification / Q000378:metabolism*; D012995:Solubility
D011957:Receptors, Opioid; D009270:Naloxone; D005048:Etorphine; D016314:Ethylketocyclazocine; D003496:Cyclazocine