title: A non-ionic vesicle lipid enhances mastoparan-stimulated GTPase activity of heterotrimeric G-proteins.
abstract: Isolated heterotrimeric G-proteins exhibit full biological activity when reconstituted into liposomes. Here, we investigated the non-ionic surfactant macrogol-260-cetylstearylether (TA 6) as an efficient vehicle for the reconstitution of G-proteins. Reconstitution efficiency of G-proteins was recorded by GTP gamma S-binding. Their biological potency was measured as basal and mastoparan-stimulated GTPase-activity. G-proteins were fully active when associated with liposomes. On the other hand, G-proteins solubilized by TA 6 micelles or reconstituted into pure TA 6 vesicles exhibited impaired biological activity. However, vesicles containing different ratios of azolectin and non-ionic TA 6 showed about 50% higher reconstitution efficiency as compared to pure liposomes. In addition, basal and mastoparan-stimulated GTPase-activity in vesicles containing an axolectin/TA 6 ratio of 3:1 were 2.7 and 9.1 fold higher than in pure liposomes, respectively. These data emphasize that the composition of the lipid membranous environment significantly influences G-protein activity.
authors.affiliation: Institut für Pharmakologie, Universitätsklinikum Rudolf Virchow, Freie Universität Berlin, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Nürnberg
authors.forename: R
authors.initials: R
authors.lastname: Hoppe
authors.forename: U
authors.initials: U
authors.lastname: Rümenapp
authors.forename: R
authors.initials: R
authors.lastname: Harhammer
authors.forename: E
authors.initials: E
authors.lastname: Nürnberg
mesh_terms: D000818:Animals; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000502:physiology*; D006868:Hydrolysis; D036341:Intercellular Signaling Peptides and Proteins; D008055:Lipids / Q000502:physiology*; D010455:Peptides; D014862:Wasp Venoms / Q000494:pharmacology
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D008055:Lipids; D010455:Peptides; D014862:Wasp Venoms; C037500:mastoparan; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins