What is a proton gradient?

A proton gradient is a difference in proton concentration across a cellular membrane, which results in a potential energy that can be harnessed by the cell to perform various functions. Proton gradients are used by cells to power ATP (adenosine triphosphate) synthesis, which is the energy currency of all cells. In cells, the proton gradient is usually created by the active transport of protons (H+) across a membrane by specialized proteins, such as proton pumps, which move the protons against the concentration gradient. The proton gradient can then be used by other proteins, such as ATP synthase, to produce ATP. Moreover, other ion channels and transporters utilize the proton gradient across the cellular membrane to transport other ions or molecules across the membrane, such as bicarbonate, sodium, potassium, calcium or amino acids. In summary, the proton gradient is a critical component of cellular energy metabolism and numerous physiological processes in cells.