Ecto-ATPase: an activation marker necessary for effector cell function.
Ecto-ATPase, a transmembrane enzyme that catalyzes the hydrolysis of extracellular ATP (ATPe) to ADP and inorganic phosphate, is expressed upon cell activation. Ecto-ATPase is inhibited by non-hydrolyzable ATP analogues, which are competitive inhibitors of the catalytic reaction, and the ATP analogue affinity label. 5'-p-(fluorosulfonyl)benzoyl adenosine (5'-FSBA), which irreversibly inhibits the catalytic activity. These nucleotide antagonists do not cross the cell membrane and are specific for ecto-ATPase in T cells, B cells and NK cells. Inhibition of ecto-ATPase by both reversible and irreversible nucleotide antagonists results in the inhibition of antigen-induced cytokine secretion and cytolytic activity of T cells. Likewise, granule release and cytolytic activity of NK cells as well as antibody secretion and spontaneous proliferation by B-cell hybridomas are inhibited. Inhibition of ecto-ATPase does not influence effector cell-target cell conjugate formation, but acts, in part, by regulating the influx of extracellular calcium that is necessary to maintain cellular activation. Thus, further elucidation of ecto-ATPase regulation and expression and its interaction with intracellular signal transduction events will provide a basis for understanding the role of the hydrolysis of ATPe by ecto-ATPase in lymphocyte effector function.
Dombrowski
K E
KE
Atlanta Research and Education Foundation/Department of Veterans Affairs Medical Center, Decatur, Georgia 30033, USA. dombrowski.kenneth_e@atlanta.va.gov
Ke
Y
Y
Brewer
K A
KA
Kapp
J A
JA
D000251:Adenosine Triphosphatases / Q000276:immunology*; D000818:Animals; D015415:Biomarkers; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000201:enzymology* / Q000276:immunology*
D015415:Biomarkers; D000251:Adenosine Triphosphatases