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How does active transport use ATP to move substances across a cell membrane?

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Artist's illustration of human nerve cells showing a central neuron with a green nucleus, branching dendrites, and glowing signals traveling along axons against a dark background. — cell Artist's conception of a human neuron.

Active transport moves substances across a cell membrane against their concentration gradients by utilizing energy derived from adenosine triphosphate (ATP).12

In primary active transport, this process is directly linked to the hydrolysis of ATP. A specialized protein, such as the sodium-potassium pump, acts as an enzyme that splits ATP to fuel the transport of ions. During this cycle:1
* The enzyme undergoes conformational changes driven by the splitting of ATP and the binding of specific ions.1
* For the sodium-potassium pump, the transfer of a phosphate group from ATP to the enzyme is catalyzed by sodium, allowing sodium to be pumped out of the cell.1
* The subsequent release of that phosphate, catalyzed by potassium, allows potassium to be pumped into the cell.1

This strict coupling of ATP hydrolysis to ion movement ensures that substances are transported even when moving from areas of low concentration to high concentration. This process is essential for maintaining cellular homeostasis and establishing electric potential across membranes.13