Proton pump

Illustration of a Respiratory Complex I, an example of a proton pump.

A proton pump is an integral membrane protein pump that builds up a proton gradient across a biological membrane. Proton pumps catalyzes 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, when comparing proton pumps- either same cell/different pump, or different cells/different pump- they will not all be evolutionarily related. Proton pumps are divided into different major classes of pumps that use different sources of energy, exhibiting different polypeptide compositions and evolutionary origins.

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