Receptor-mediated activation of G-proteins by κ opioid agonists in frog (Rana esculenta) brain membranes

M. Rottmann, G. Fábián, K. Spicher, S. Offermanns, M. Szucs

Research output: Contribution to journalArticle

6 Citations (Scopus)


This study delineates the heterotrimeric guanine nucleotide binding regulatory protein (G-protein) types in frog (Rana esculenta) brain membranes and their activation by κ opioid agonists. Ethylketocyclazocine (EKC), trans-(±)-3,4-dichloro-N-methy-N-(2-[1- pyrrolidinyl]cyclohexyl)benzeneacetamide (U-50,488) and bremazocine displayed dose-dependent, norbinaltorphimine-reversible stimulation of guanosine-5'-O- (3-[35S]thio)triphosphate ([35S]GTPγS) binding in crude membrane preparations. G-proteins were identified by Western-blotting using previously characterized specific antisera that were generated against mammalian G- protein α-subunits and β-subunits. A photoreactive guanosine 5'- triphosphate (GTP) analog, [α-32P]GTP azidoanilide ([α-32P]AA-GTP) irreversibly labeled four proteins in the molecular weight range of 39-43 kDa. Ethylketocyclazocine and U-50,488 stimulated photolabelling of these proteins among which the 39 kDa band comigrated with the protein specifically labelled with the α12 antibody and the 40 kDa band was identified as α01. The other two bands were also stained with the α(common) antibody, but were not further identified. These results suggest that the endogenously expressed κ opioid receptors that are present in frog brain interact with multiple G-proteins in situ. Furthermore, the structure of most G-proteins seems to be well preserved during phylogenesis.

Original languageEnglish
Pages (from-to)467-474
Number of pages8
JournalBrain Research Bulletin
Issue number5
Publication statusPublished - Mar 15 1998


  • Functional coupling
  • Western-blotting
  • [S]GTPγS binding
  • κ opioid agonist

ASJC Scopus subject areas

  • Neuroscience(all)

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