Proton pump

A proton pump is an integral membrane protein pump that builds up a proton gradient across a biological membrane. Proton pumps catalyze the following reaction:

H⁺
_{[on one side of a biological membrane]} + energy ⇌ H⁺
_{[on the other side of the membrane]}

Mechanisms are based on energy-induced conformational changes of the protein structure or on the Q cycle.

During evolution, proton pumps have arisen independently on multiple occasions. Thus, not only throughout nature but also within single cells, different proton pumps that are evolutionarily unrelated can be found. Proton pumps are divided into different major classes of pumps that use different sources of energy, have different polypeptide compositions and evolutionary origins.