title: Human mu-opioid receptor overexpressed in Sf9 insect cells functionally coupled to endogenous Gi/o proteins.
abstract: Human mu-opioid receptor (HmuOR) with a tag of six consecutive histidines at its carboxyl terminus had been expressed in recombinant baculovirus infected Sf9 insect cells. The maximal binding capacity for the [3H] diprenorphine and [3H]ohmefentanyl (Ohm) were 9.1 +/- 0.7 and 6.52 +/- 0.23 nmol/g protein, respectively. The [3H] diprenorphine or [3H] Ohm binding to the receptor expressed in Sf9 cells was strongly inhibited by mu-selective agonists [D-Ala2, N-methyl-Phe4, glyol5]enkephalin (DAGO), Ohm, and morphine, but neither by delta nor by kappa selective agonist. Na+ (100 mM) and GTP (50 microM) could reduce HmuOR agonists etorphine and Ohm affinity binding to the overexpressed HmuOR. mu-selective agonists DAGO and Ohm effectively stimulated [35S]GTP-gammaS binding (EC50 = 2.7 nM and 6.9 nM) and inhibited forskolin- stimulated cAMP accumulation (IC50 = 0.9 nM and 0.3 nM). The agonist-dependent effects could be blocked by opioid antagonist naloxone or by pretreatment of cells with pertussis toxin (PTX). These results demonstrated that HmuOR overexpressed in Sf9 insect cells functionally coupled to endogenous G(i/o) proteins.
authors.affiliation: Shanghai Institute of Materia Medica, Shanghai Academy of Life Sciences, Chinese Academy of Sciences.
authors.forename: Q
authors.initials: Q
authors.lastname: Wei
authors.forename: D H
authors.initials: DH
authors.lastname: Zhou
authors.forename: Q X
authors.initials: QX
authors.lastname: Shen
authors.forename: J
authors.initials: J
authors.lastname: Chen
authors.forename: L W
authors.initials: LW
authors.lastname: Chen
authors.forename: T L
authors.initials: TL
authors.lastname: Wang
authors.forename: G
authors.initials: G
authors.lastname: Pei
authors.forename: Z Q
authors.initials: ZQ
authors.lastname: Chi
mesh_terms: D000818:Animals; D002460:Cell Line; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D015870:Gene Expression; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D017450:Receptors, Opioid, mu / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D018411:Spodoptera / Q000166:cytology
chemical_list: D017450:Receptors, Opioid, mu; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D020962:Heterotrimeric GTP-Binding Proteins