The Na/K-ATPase actively generates the physiological sodium and potassium concentration gradients across the plasma membrane of animal cells. The transporter is comprised of at least two mandatory subunits. The large catalytic alpha subunit contains approximately 1,000 residues with 10 transmembrane domains and is required for ion transport and ligand binding. The Na/K-ATPase also contains a beta subunit, which is a type II transmembrane glycoprotein with 300 amino acids. We have used voltage clamp fluorometry to determine distance constraints between the alpha and beta subunits. Previously, two models, based on electron microscopy and biochemical studies for the architecture of the Na/K-ATPase have been proposed. Utilizing, voltage-clamp fluorometry and FRET, we have investigated the relative orientation of the alpha and beta subunits of the ion pump

We have also investigated the relative movement between the alpha and beta subunit proximal to the plasma membrane as the ion pump shuttles between the two main conformational states as described by the Albers-Post scheme. The results from this study have determined that there is a conformational re-arrangement between the transmembrane domains of the two subunits during ion transport.