RECONSTITUTION OF A PURIFIED MU-OPIOID BINDING-PROTEIN IN LIPOSOMES - SELECTIVE, HIGH-AFFINITY, GTP-GAMMA-S-SENSITIVE MU-OPIOID AGONIST BINDING IS RESTORED

An opioid binding protein (GBP) purified to homogeneity from bovine striatal membranes has been reconstituted in liposomes. The liposomes were produced by PEG-precipitation of OBP in the presence of a CHAPS extract of bovine striatum, devoid of opioid binding. High affinity μ-agonist binding was restored. The binding was selective for μ-agonists, stereospecific and inhibited by GTPγS. These results demonstrate that there is recoupling of OBP with G-protein and confirm our earlier evidence that the purified OBP is a μ-opioid binding site. © 1993 Academic Press, Inc.