Three-dimensional structure of renal Na,K-ATPase determined by electron microscopy of membrane crystals.

The three-dimensional structure of Na,K-ATPase was determined by electron microscopy and image processing. Tilt series of negatively stained membrane crystals were recorded. The projections were analyzed by Fourier methods and the data combined to a 3-D model. The unit cell contains two rod-shaped stain-deficient regions interpreted as alpha beta-promoters of Na,K-ATPase. The rods are related by dyad axes oriented perpendicular to the membrane. Outside the lipid bilayer the rods contact different protein units on the two sides of the membrane.