This proposal is directed at generating and characterizing monoclonal antibodies to the multiple opioid receptors. In turn, these antibodies will be used to characterize and purify the opioid receptors. Monoclonal antibodies to the receptor will be screened by radioimmunoassay, immunoprecipitation and on their ability to inhibit opiate binding. One antibody already generated, OR-465.3, will be studied in greater detail. Studies will be initiated to ascertain which type of opioid receptor, this antibody is directed against. Additional monoclonal antibodies to the receptor will be generated by using rat neural membranes, solubilized opioid receptor and neuroblastoma-glioma, NG108-15, membranes as antigens. Antibodies specific for each type of opioid receptor is the ultimate goal. Antibodies will be tested for their ability to inhibit opiate binding to rat neural membranes and to solubilized receptor preparations. Their effect on opiate binding to peripheral tissues such as the guinea pig ileum and the mouse vas deferens will be examined. Immunoprecipitation of the receptor from a solubilized preparation will be used to identify antibodies that interact with the receptor but, not at its opiate binding site. Antibodies will be tested by a Western blot technique to ascertain which protein(s) they're directed against. Finally, these antibodies will be used to purify the opiate binding protein(s) that they recognize. By using monoclonal antibodies, it will be possible to probe the opioid receptor (s) directly.