The Sodium-Potassium Pump Chapter 5

Step 5 (dephosphorylation)

The binding of the potassium ions causes the phosphate group to be released.

Step 4

The new shape will allow two potassium ions to bind from the outside.

Step 3

With the new shape the sodium ions now face the cell exterior. The ions don't bind as well to the new shape and they are released to the outside.

Step 2 (phosphorylation)

ATP adds a phosphate group to the carrier protein. This causes the protein to change shape.

Step 1

Three sodium ions bind to the cytoplasmic side of the carrier protein.

The Sodium-Potassium Pump (6 steps)

*Allows cells to maintain a low internal concentration of Na+and a high internal concentration of K+. This is an example of active transport. *Each pump performs these six steps 100 times per second (maximum speed). The sodium potassium pump is needed to maintain nerve cell voltage and also to drive other transport processes.

Step 6

Once the phosphate group is released the protein returns to its' original shape. The two potassium ions now face the interior of the cell. The original shape doesn't allow the potassium ions to remain bound to the protein. The potassium ions are released inside the cell.