ATP-A activity in cultured human glioma cells
Wieslander, A.; Edström, A.; Kanje, M.; Sommarin, Y.
Cellular and Molecular Biology Including Cyto-Enzymology 26(1): 59-63
1980
ISSN/ISBN: 0145-5680 PMID: 6248222 Document Number: 166294
ATP hydrolysis was measured in homogenates of cultured human glioma cells, 138 MG. ATPase activity was stimulated by Mg, Na and K, but unaffected by ouabain. Maximal ATPase activity, obtained at pH 8.5 in the presence of Mg, Na and K ions, was 7.1 i.u. (.mu.mole released phosphate per mg protein and h) with an apparent Km of 0.27 mM ATP. NaK-ATPase activity defined as the difference between total-ATPase and Mg-ATPase was 0.7 i.u. and represented 10% of total-ATPase. Intracellular Na and K concentrations were assessed. The comparatively low NaK-ATPase activity in glioma cannot be related to levels of Na and K divergent from those reported for brain slices from adult rat brain. Dibutyryl cyclic AMP induced morphological differentiation of 138 MG cells. This process was associated with 50% increase in NaK-ATPase activity.