AJP - Cell Physiology, Vol 248, Issue 3 247-C251, Copyright © 1985 by American Physiological Society
Comparison of subunits of cardiac, brain, and kidney Na+-K+-ATPase
A. McDonough and C. Schmitt
Na+-K+-ATPase is in low abundance in cardiac tissue. Therefore, we utilized
antibodies to detect the cardiac Na+-K+-ATPase subunits and to compare
their characteristics with those of kidney and brain Na+-K+-ATPase
subunits. By using crude preparations of heart membranes as well as
purified sarcolemmal membranes from guinea pig hearts, we resolved peptides
by polyacrylamide gel electrophoresis in the presence of sodium dodecyl
sulfate, blotted them onto diazotized paper, and detected Na+-K+-ATPase
subunits with antibodies generated against highly purified kidney
Na+-K+-ATPase holoenzyme. We tested the hypothesis that the two families of
ouabain-binding affinities described in heart are due to two forms of
alpha-subunit, analogous to the two forms with different affinities for
ouabain described in brain. Although the antibodies did detect two forms of
catalytic subunit in brain (alpha and alpha +), only one form of alpha was
detected in the heart membranes, with the same electrophoretic mobility as
kidney alpha. Cardiac beta-subunit could also be detected with the
antikidney antibodies. It had a similar electrophoretic mobility to that
described for kidney beta, whereas brain beta had a higher mobility.
