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.