Sodium/Potassium Pump

The Sodium/Potassium Pump puts Na⁺ outside the cell and K⁺ inside the cell.

• 3Na⁺ mols inside bind to receptor
• This stimulates phosphorylation of receptor by ATP.
• This alters receptor shape, shape change dumps Na⁺ onto inside.
• Open receptors bind 2K⁺ ions outside.
• K⁺ binding triggers phosphate release.
• This restores original conformation.
• K⁺ released inside, NA⁺ sites become available.
• Net: 1 ATP lost; 3 Na⁺ outside; 2 K⁺ inside.