title: The influence of monovalent cations on trimeric G protein G(i)1α activity in HEK293 cells stably expressing DOR-G(i)1α (Cys(351)-Ile(351)) fusion protein.
abstract: The effect of monovalent cations on trimeric G protein G(i)1α was measured at equimolar concentration of chloride anion in pertussis-toxin (PTX)-treated HEK293 cells stably expressing PTX-insensitive DOR- G(i)1α (Cys(351)-Ile(351)) fusion protein by high-affinity [(35)S]GTPgammaS binding assay. The high basal level of binding was detected in absence of DOR agonist and monovalent ions and this high level was inhibited with the order of: Na(+) > K(+) > Li(+). The first significant inhibition was detected at 1 mM NaCl. The inhibition by monovalent ions was reversed by increasing concentrations of DOR agonist DADLE. The maximum DADLE response was also highest for sodium and decreased in the order of: Na(+) > K(+) ~ Li(+). Our data indicate i) an inherently high activity of trimeric G protein G(i)1α when expressed within DOR- G(i)1α fusion protein and determined in the absence of monovalent cations, ii) preferential sensitivity of DOR- G(i)1alpha to sodium as far as maximum of agonist response is involved.
authors.affiliation: Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
authors.forename: M
authors.initials: M
authors.lastname: Vošahlíková
authors.forename: P
authors.initials: P
authors.lastname: Svoboda
mesh_terms: D002414:Cations, Monovalent; D003545:Cysteine / Q000235:genetics*; D016308:Enkephalin, Leucine-2-Alanine / Q000494:pharmacology; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007532:Isoleucine / Q000235:genetics*; D008672:Metals, Alkali / Q000494:pharmacology*; D055503:Protein Multimerization; D017465:Receptors, Opioid, delta / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D002414:Cations, Monovalent; D008672:Metals, Alkali; D017465:Receptors, Opioid, delta; D011993:Recombinant Fusion Proteins; D007532:Isoleucine; D016308:Enkephalin, Leucine-2-Alanine; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D003545:Cysteine