EXPRESSION AND PHARMACOLOGICAL CHARACTERIZATION OF THE HUMAN MU-OPIOID RECEPTOR IN THE METHYLOTROPHIC YEAST PICHIA-PASTORIS

The human mu-opioid receptor cDNA from which the 32 amino-terminal cod ons sere substituted bg the Saccharomyces cerevisiae alpha-mating fact or signal sequence lias been expressed in the methylotrophic yeast Pic hia pastoris using the host promoter of the alcohol oxidase-1 gene, Ce ll membranes exhibited specific and saturable binding of the opioid an tagonist [H-3]diprenorphine (K-d = 0,2 nM and B-max = 400 fmol/mg prot ein or 800 sites/cell), Competition studies,vith non-selective, and mu -, delta- and kappa-selective opioid agonists and antagonists revealed a typical mu-opioid. receptor binding profile, suggesting proper fold ing of the protein in yeast membranes.