Abstract
The Na+,K+-ATPase belongs to the P-ATPase family, whose characteristic property is the formation of a phosphorylated intermediate. The enzyme is also a defined target for cardiotonic steroids which inhibit its functional activity and initiate intracellular signaling. Here we describe the 4.6 Å resolution crystal structure of the pig kidney Na+,K+-ATPase in its phosphorylated form stabilized by high affinity binding of the cardiotonic steroid ouabain. The steroid binds to a site formed at transmembrane segments αM1-αM6, plugging the ion pathway from the extracellular side. This structure differs from the previously reported low affinity complex with potassium. Most importantly, the A domain has rotated in response to phosphorylation and αM1-2 move towards the ouabain molecule, providing for high affinity interactions and closing the ion pathway from the extracellular side. The observed re-arrangements of the Na+,K+-ATPase stabilized by cardiotonic steroids may affect protein-protein interactions within the intracellular signal transduction networks.
| Original language | English |
|---|---|
| Journal | Journal of Structural Biology |
| Volume | 174 |
| Issue | 2 |
| Pages (from-to) | 296-306 |
| Number of pages | 11 |
| ISSN | 1047-8477 |
| DOIs | |
| Publication status | Published - 2011 |
Keywords
- Animals
- Binding Sites
- Cardiotonic Agents
- Crystallography, X-Ray
- Magnesium
- Models, Molecular
- Ouabain
- Phosphorylation
- Protein Binding
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Sodium-Potassium-Exchanging ATPase
- Swine