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Identification and partial characterization of ectoATPase expressed by immortalized B lymphocytes
K E Dombrowski1, K A Brewer, J R Maleckar
1Department of Veterans Affairs Medical Center, Amarillo, Texas 79106, USA.
Archives of Biochemistry and Biophysics
|April 1, 1997
Summary
EctoATPases, enzymes hydrolyzing ATP, are present on activated B lymphocytes, potentially marking B cell activation. Mammalian and avian ectoATPases share conserved properties.
Area of Science:
- Biochemistry
- Immunology
- Cell Biology
Background:
- EctoATPases are extracellular enzymes that break down ATP.
- Their expression varies across different cell types, including B lymphocytes.
Purpose of the Study:
- To investigate ectoATPase expression in B lymphocytes.
- To characterize the kinetic and immunological properties of ectoATPases.
- To determine if ectoATPase can serve as a marker for B cell activation.
Main Methods:
- Enzyme activity assays (K(m), Vmax) using ATP.
- Inhibition studies with ADP and nucleoside triphosphates.
- Western blot analysis with anti-ectoATPase antibodies on cell membranes.
Main Results:
- EctoATPase activity was detected in activated/immortalized B cells, but not in non-transformed B cells.
- Kinetic parameters (K(m), Vmax) and Mg2+ dependence were determined.
- Western blots identified a 66-kDa protein in reduced murine and human B cell membranes, suggesting conserved epitopes.
Conclusions:
- EctoATPase expression may indicate B cell activation.
- Mammalian and avian ectoATPases exhibit conserved interspecies immunological epitopes and kinetic characteristics.