title: Gsalpha-selective G protein antagonists.
abstract: Suramin acts as a G protein inhibitor because it inhibits the rate-limiting step in activation of the Galpha subunit, i.e., the exchange of GDP for GTP. Here, we have searched for analogues that are selective for Gsalpha. Two compounds have been identified: NF449 (4,4',4",4'"-[carbonyl-bis[imino-5,1,3-benzenetriyl bis-(carbonylimino)]]tetrakis-(benzene-1,3-disulfonate) and NF503 (4, 4'-[carbonylbis[imino-3,1-phenylene-(2, 5-benzimidazolylene)carbonylimino]]bis-benzenesulfonate). These compounds (i) suppress the association rate of guanosine 5'-[gamma-thio]triphosphate ([35S]GTP[gammaS]) binding to Gsalpha-s but not to Gialpha-1, (ii) inhibit stimulation of adenylyl cyclase activity in S49 cyc- membranes (deficient in endogenous Gsalpha) by exogenously added Gsalpha-s, and (iii) block the coupling of beta-adrenergic receptors to Gs with half-maximum effects in the low micromolar range. In contrast to suramin, which is not selective, NF503 and NF449 disrupt the interaction of the A1-adenosine receptor with its cognate G proteins (Gi/Go) at concentrations that are >30-fold higher than those required for uncoupling of beta-adrenergic receptor/Gs tandems; similarly, the angiotensin II type-1 receptor (a prototypical Gq-coupled receptor) is barely affected by the compounds. Thus, NF503 and NF449 fulfill essential criteria for Gsalpha-selective antagonists. The observations demonstrate the feasibility of subtype-selective G protein inhibition.
authors.affiliation: Institute of Pharmacology, University of Vienna, Währinger Strasse 13a, A-1090 Austria.
authors.forename: M
authors.initials: M
authors.lastname: Hohenegger
authors.forename: M
authors.initials: M
authors.lastname: Waldhoer
authors.forename: W
authors.initials: W
authors.lastname: Beindl
authors.forename: B
authors.initials: B
authors.lastname: Böing
authors.forename: A
authors.initials: A
authors.lastname: Kreimeyer
authors.forename: P
authors.initials: P
authors.lastname: Nickel
authors.forename: C
authors.initials: C
authors.lastname: Nanoff
authors.forename: M
authors.initials: M
authors.lastname: Freissmuth
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001557:Benzenesulfonates / Q000494:pharmacology*; D001562:Benzimidazoles / Q000494:pharmacology*; D004926:Escherichia coli; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000037:antagonists & inhibitors*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D020120:Iodocyanopindolol; D007545:Isoproterenol / Q000378:metabolism; D015513:Oncogene Proteins / Q000037:antagonists & inhibitors*; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D011945:Receptors, Angiotensin / Q000378:metabolism; D018047:Receptors, Purinergic P1 / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012504:Saralasin / Q000494:pharmacology
chemical_list: C110259:4,4'-(carbonylbis(imino-3,1-phenylene(2,5-benzimidazolylene)carbonylimino))bisbenzenesulfonate; C110258:4,4,',4'',4'''-(carbonylbis(imino-5,1,3-benzenetriylbis(carbonylimino)))tetrakis(benzene-1,3-disulfonate); D001557:Benzenesulfonates; D001562:Benzimidazoles; D015513:Oncogene Proteins; D011943:Receptors, Adrenergic, beta; D011945:Receptors, Angiotensin; D018047:Receptors, Purinergic P1; D011994:Recombinant Proteins; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D020120:Iodocyanopindolol; D010869:Pindolol; D019205:GTP-Binding Protein alpha Subunits, Gs; D000262:Adenylyl Cyclases; D012504:Saralasin; D007545:Isoproterenol