1. With the enzyme oriented towards the cell's interior, the carrier has a high affinity for sodium ions. Three ions bind to the protein.
2. The protein carrier hydrolyzes ATP and a low-energy phosphate group attaches to it.
3. As a result, the carrier changes shape and reorients itself towards the membrane's exterior. The protein’s affinity for sodium decreases and the three sodium ions leave the carrier.
4. The shape change increases the carrier’s affinity for potassium ions, and two such ions attach to the protein. Subsequently, the low-energy phosphate group detaches from the carrier.
5. With the phosphate group removed and potassium ions attached, the carrier protein repositions itself towards the cell's interior.
6. The carrier protein, in its new configuration, has a decreased affinity for potassium, and the two ions moves into the cytoplasm. The protein now has a higher affinity for sodium ions, and the process starts again.