Section 3 Lesson 3 – The Sodium Potassium Pump

1. Section 3Lesson 3– The Sodium Potassium Pump

2. Active Transport Active transport requires energy and allows movement against a concentration gradient.

3. The Importance of the Sodium Potassium Pump Powering the sodium potassium pump can be responsible 30% of the energy consumption in a cell. For every 3 Na + ions pumped out of a cell 2 K+ ions are pumped in. This creates a potential difference. This makes the cytoplasm negatively charged in comparison to the extracellular environment. The electrochemical gradient this creates provides energy for other active transport processes.

4. The Importance of the Sodium Potassium Pump The potential difference produced is also important for generating resting potential in nerve cells (so they can fire signals).

5. The Importance of the Sodium Potassium Pump Digoxin (found in foxgloves) is a sodium potassium pump inhibitor making it toxic to cells. At low concentrations it can have medicinal uses. It is used for the treatment of heart diseases such as atrial fibrillation and atrial flutter.

6. Na+ -K+ -ATPase The complex responsible for sodium potassium pump is called Na+-K+-ATPase and is made up of 4 protein subunits. Sodium Potassium ATPase • Features of the Sodium Potassium Pump • It is a transmembrane carrier protein • It has 3 binding sites for Na+ • It has 2 binding sites for K+ • There is a phosphorylation site where a phosphate group is accepted fro ATP • The 2 different conformations of the protein are controlled by the phosphorylation

7. Six Stages of Sodium Potassium Pump 3 binding sites for Na+ are exposed in the cytosol (inside the cell) and 3 Na+ ions bind. Once the 3 ions are attached a phosphate group from ATP is broken off and binds to the Na+K+ATPase. This phosphorylation causes a conformational change in the enzyme (this is an example of covalent modification). The change in shape affects the affinity (binding) of the Na+ ions causing them to be released into the outside of the cell. This same change in shape allows for the exposure of 2 K+ ion binding sites outside the cell. The K+ ions bind to the sites causing the phosphate group inside the cell to be released from the pump. This in turn causes yet another change to the conformation causing the 2 K+ ions to be released into the cell. Animation

10. Your Tasks Create a poster showing the 6 stages of the Sodium Potassium Pump. Update your glossary. Complete Scholar Tasks. Due Monday December 17th