title: Functional coupling of GABA(B) receptors with G proteins that are sensitive to N-ethylmaleimide treatment, suramin, and benzalkonium chloride in rat cerebral cortical membranes.
abstract: Although it is known that GABA(B) receptors are negatively coupled to adenylyl cyclase, the detailed selectivity of functional interaction between GABA(B) receptors and Gi subfamily members is still ambiguous. (+/-)-Baclofen-stimulated high-affinity GTPase activity, which was competitively antagonized by 2-hydroxy-saclofen, was attenuated by pretreatment of the membranes with N-ethylmaleimide (NEM) in a concentration- and incubation period-dependent manner. The NEM-pretreated (50 microM, 15 min at 4 degrees C) membranes restored the (+/-)-baclofen-sensitive high-affinity GTPase activity when reconstituted with pertussis toxin-sensitive bovine brain G proteins. Among recombinant rat Galpha subunits, G(i alpha(-2)) appeared most effective as compared with other subunits (G(i alpha(-2)) > G(i alpha(-3) > G(i alpha(-1) = G(o alpha). The GABA(B) receptor-mediated high-affinity GTPase activity was also completely eliminated by 100 microM suramin and by 100 microM benzalkonium chloride. These results indicate that GABA(B) receptors in rat cerebral cortex couple to NEM-sensitive G proteins, in particular Gi2, which are sensitive to suramin and benzalkonium chloride.
authors: Department of Psychiatry, Hokkaido University School of Medicine, Sapporo, Japan.
authors: Y
authors: Y
authors: Odagaki
authors: N
authors: N
authors: Nishi
authors: T
authors: T
authors: Koyama
mesh_terms: D037361:Adenylate Cyclase Toxin; D000818:Animals; D001418:Baclofen / Q000031:analogs & derivatives* / Q000494:pharmacology; D001548:Benzalkonium Compounds / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D004305:Dose-Response Relationship, Drug; D005033:Ethylmaleimide / Q000494:pharmacology*; D018756:GABA Antagonists / Q000494:pharmacology; D020558:GTP Phosphohydrolases / Q000187:drug effects / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D037342:Pertussis Toxin; D051381:Rats; D017207:Rats, Sprague-Dawley; D018080:Receptors, GABA-B / Q000187:drug effects* / Q000378:metabolism; D013347:Subcellular Fractions / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D013498:Suramin / Q000494:pharmacology*; D010566:Virulence Factors, Bordetella / Q000378:metabolism
chemical_list: D037361:Adenylate Cyclase Toxin; D001548:Benzalkonium Compounds; D018756:GABA Antagonists; D018080:Receptors, GABA-B; D010566:Virulence Factors, Bordetella; D013498:Suramin; D037342:Pertussis Toxin; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D001418:Baclofen; C080629:saclofen; D005033:Ethylmaleimide