Association of renal Na,K-ATPase alpha-subunit with the beta- and gamma-subunits based on cryoelectron microscopy

• Na,K-ATPase transports Na+ and K+ across cell membranes and consists of alpha- and beta-subunits. Na,K-ATPase also associates with small FXYD proteins that regulate the activity of the pump. We have used cryoelectron microscopy of two-dimensional crystals including data to 8 A resolution to determine the three-dimensional (3-D) structure of renal Na,K-ATPase containing FXYD2, the gamma-subunit. A homology model for the a- subunit was calculated from a Ca2+-ATPase structure and used to locate the additional beta- and gamma-subunits present in the 3-D map of Na,K-ATPase. Based on the 3-D map, the beta- subunit is located close to transmembrane helices M8 and M10 and the gamma-subunit is adjacent to helices M2 and M9 of the alpha-subunit.

Nyckelord

Na

K-ATPase

cryoelectron microscopy

gamma-subunit

beta-subunit

FXYD2

calcium-pump

crystal-structure

3-dimensional structure

sarcoplasmic-reticulum

cross-links

atpase

resolution

binding

domain

ca2+-atpase

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