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The role of G protein B subunits in the release of ATP from human erythrocytes

100%

Sprague R. S., Bowles E. A., Olearczyk J. J., Stephenson A. H., Lonigro A. J.

Journal of Physiology and Pharmacology

2002

tom 53

nr 4,1

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 ß submits present in these erythrocyte membranes. The activity of Gi was stimulated by incubation of erythrocytes (20% hematocrit) with mastoparin (10 µM). ATP release was measured using the luciferin/luciferase assay. Heterotrimeric G protein ß subunits present in erythrocyte membranes were resolved using gel electrophoresis and subunit specific antibodies. Incubation of human erythrocytes with mastoparan (an activator ofGi/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 ß 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 ß submits associated with this G protein in the human erythrocyte.

Cross-talk between the ATP and ADP nucleotide receptor signalling pathways in glioma C6 cells

84%

Czajkowski R., Baranska J.

Acta Biochimica Polonica

2002

tom 49

nr 4

In this review we summarize the present status of our knowledge on the enzymes involved in the extracellular metabolism of nucleotides and the receptors involved in nucleotide signalling. We focus on the mechanism of the ATP and ADP signalling pathways in glioma C6, representative of the type of nonexcitable cells. In these cells, ATP acts on the P2Y2 receptor coupled to phospholipase C, whereas ADP on two distinct P2Y receptors: P2Y1 and P2Y12. The former is linked to phospholipase C and the latter is negatively coupled to adenylyl cyclase. The possible cross-talk between the ATP-, ADP- and adenosine-induced pathways, leading to simultaneous regulation of inositol 1,4,5-trisphosphate and cAMP mediated signalling, is discussed.

Ograniczanie wyników

1 Acta Biochimica Polonica

1 Journal of Physiology and Pharmacology

1 Baranska J.

1 Bowles E. A.

1 Czajkowski R.

1 Lonigro A. J.

1 Olearczyk J. J.

1 Sprague R. S.

1 Stephenson A. H.

2 2002

Wyniki wyszukiwania

The role of G protein B subunits in the release of ATP from human erythrocytes

Cross-talk between the ATP and ADP nucleotide receptor signalling pathways in glioma C6 cells