title: Characterization of the membrane-associated GTPase activity: effects of chemotactic factors and toxins.
abstract: Membranes prepared from rabbit neutrophils exhibit GTPase activity which can be stimulated by the chemotactic factor fMet-Leu-Phe. The maximum contribution of the ATPase activities to the basal and the fMet-Leu-Phe-stimulated GTPase activities are less than 20% and 9%, respectively. The basal GTPase activity has a Vmax = 34.2 +/- 1.3 (pmol/mg protein, min) and a Km = 0.39 +/- 0.03 microM; and the fMet-Leu-Phe-stimulated has a Vmax = 52.3 +/- 2.5 (pmol/mg protein, min), and a Km = 0.29 +/- 0.02 microM. The GTPase activity can be stimulated by fMet-Leu-Phe and leukotriene B4. Unlike these two chemotactic factors, concanavalin A does not stimulate this GTPase activity. In addition, the rise in intracellular concentration of free calcium produced by concanavalin A is not inhibited by pertussis toxin treatment. Both the basal and stimulated GTPase activities are affected by pertussis toxin, cholera toxin and N-ethylmaleimide.
authors.affiliation: Department of Physiology, University of Connecticut Health Center, Farmington 06032.
authors.forename: C
authors.initials: C
authors.lastname: Pelz
authors.forename: T
authors.initials: T
authors.lastname: Matsumoto
authors.forename: T F
authors.initials: TF
authors.lastname: Molski
authors.forename: E L
authors.initials: EL
authors.lastname: Becker
authors.forename: R I
authors.initials: RI
authors.lastname: Sha'afi
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000201:enzymology*; D002630:Chemotactic Factors / Q000494:pharmacology; D002772:Cholera Toxin / Q000494:pharmacology; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D007700:Kinetics; D007975:Leukotriene B4 / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology*; D037342:Pertussis Toxin; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D011817:Rabbits; D013268:Stimulation, Chemical; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D002630:Chemotactic Factors; D008565:Membrane Proteins; D010566:Virulence Factors, Bordetella; D007975:Leukotriene B4; D009240:N-Formylmethionine Leucyl-Phenylalanine; D002772:Cholera Toxin; D037342:Pertussis Toxin; D010744:Phosphoric Monoester Hydrolases; D020558:GTP Phosphohydrolases