title: The role of G protein beta subunits in the release of ATP from human erythrocytes.
abstract: Previously, we demonstrated that adenosine triphosphate (ATP) is released from human erythrocytes in response to mechanical deformation and that this release requires activation of a signal-transduction pathway involving adenylyl cyclase and the heterotrimeric G protein, Gs. Here we investigate the role of heterotrimeric G proteins of the Gi subtype in the release of ATP from human erythrocytes. In addition, we determined the profile of heterotrimeric G protein beta subunits present in these erythrocyte membranes. The activity of Gi was stimulated by incubation of erythrocytes (20% hematocrit) with mastoparin (10 microM). ATP release was measured using the luciferin/luciferase assay. Heterotrimeric G protein beta subunits present in erythrocyte membranes were resolved using gel electrophoresis and subunit specific antibodies. Incubation of human erythrocytes with mastoparan (an activator of Gi/o) resulted in a 4.1 +/- 0.6-fold increase in ATP present in the medium (P<0.01). Human erythrocyte membranes stain positively for beta subunit types 1, 2, 3 and 4, all of which been reported to activate of some isoforms of adenylyl cyclase. Activation of the heterotrimeric G protein, Gi, results in ATP release from erythrocytes. This effect is may be related to the activity of beta subunits associated with this G protein in the human erythrocyte.
authors.affiliation: Saint Louis University School of Medicine, MO 63104, USA. spraguer@slu.edu
authors.forename: R S
authors.initials: RS
authors.lastname: Sprague
authors.forename: E A
authors.initials: EA
authors.lastname: Bowles
authors.forename: J J
authors.initials: JJ
authors.lastname: Olearczyk
authors.forename: A H
authors.initials: AH
authors.lastname: Stephenson
authors.forename: A J
authors.initials: AJ
authors.lastname: Lonigro
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D020962:Heterotrimeric GTP-Binding Proteins / Q000502:physiology*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D009994:Osmolar Concentration; D010455:Peptides; D020033:Protein Isoforms / Q000502:physiology; D013997:Time Factors; D014862:Wasp Venoms / Q000494:pharmacology
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D020033:Protein Isoforms; D014862:Wasp Venoms; C037500:mastoparan; D000255:Adenosine Triphosphate; D020962:Heterotrimeric GTP-Binding Proteins