Ouabain resistance conferred by expression of the cDNA for a murine Na ⁺,K⁺-ATPase α subunit

The molecular basis for the marked difference between primate and rodent cells in sensitivity to the cardiac glycoside ouabain has been established by genetic techniques. A complementary DNA encoding the entire α₁ subunit of the mouse Na⁺- and K⁺-dependent adenosine triphosphatase (ATPase) was inserted into the expression vector pSV2. This engineered DNA molecule confers resistance against 10^-4 M ouabain to monkey CV-1 cells. Deletion of sequences encoding the carboxyl terminus of the α₁ subunit abolish the activity of the complementary DNA. The ability to assay the biological activity of this ATPase in a transfection protocol permits the application of molecular genetic techniques to the analysis of structure-function relationships for the enzyme that establishes the internal Na⁺/K⁺ environment of most animal cells. The full-length α₁ subunit complementary DNA will also be useful as a dominant selectable marker for somatic cell genetic studies utilizing ouabain-scnsitive cells.