Document Type


Publication Date

Spring 4-6-2007


Recent studies have ascribed many non-pumping functions to the Na/K-ATPase. Here, we present experimental evidence demonstrating that over half of the plasma membrane Na/KATPase in LLC-PK1 cells is performing cellular functions other than ion pumping. This “non-pumping” pool of Na/K-ATPase, like the pumping pump, binds ouabain. Depletion of either cholesterol or caveolin-1 moves some of the “non-pumping” Na/KATPase into the pumping pool. Graded knock-down of the 1 subunit of the Na/K-ATPase eventually results in loss of this “non-pumping” pool while preserving the pumping pool. Our prior studies indicate that a loss of the non-pumping pool is associated with a loss of receptor function as evidenced by the failure of ouabain administration to induce the activation of Src and/or ERK. Therefore, our new findings suggest that a substantial amount of surface-expressed Na/K-ATPase, at least in some types of cells, may function as non-canonical ouabain-binding receptors.


The version of record is available from the publisher at This research was originally published in The Journal of Biological Chemistry. Man Liang, Jiang Tian, Lijun Liu, Sandrine Pierre, Jiang Liu, Joseph Shapiro, and Zi-Jian Xie. Identification of a pool of non-pumping Na/K-ATPase. Journal of Biological Chemistry. 2007; 282:10585-10593. © the American Society for Biochemistry and Molecular Biology. Reprinted with permission. All rights reserved. DOI 10.1074/jbc.M609181200