ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract: Analysis of purified Na+, K+-ATPase from cat and human cortex by sodium dodecyl sulfate-polyacrylamide gel electrophoresis reveals two large catalytic subunits called α(-) (lower molecular weight) and α(+) (higher molecular weight). Differences in K+ dephosphorylation of these two molecular forms have been investigated by measuring the phosphorylation level of each protein after their separation on sodium dodecyl sulfate gels. In the presence of Na+, Mg2+, and ATP, both subunits are phosphorylated. Increasing concentrations (from 0 to 3 mM) of K+ induce progressive dephosphorylation of both α-subunits, although the phosphoprotein content of α(-) is decreased significantly less than that of α(+). Ka values of α(-) for K+ are 40% and 50% greater in cat and human cortex, respectively, than values of α(+), α(-) and α(+) are thought to be localized in specific cell types of the brain: α(-) is the exclusive form of nonneuronal cells (astrocytes), whereas α(+) is the only form of axolemma. Our results support the hypothesis that glial and neuronal Na+, K+-ATPases are different molecular entities differing at least by their K+ sensitivity. Results are discussed in relation to the role of glial cells in the regulation of extracellular K+ in brain.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1990.tb13292.x
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