Proton pump

As proton pump are in the biochemistry and physiology generally transmembrane proteins called, the protons through a biological membrane , against an electrochemical gradient , transport . It is a large and inconsistent group of proteins. A rough distinction is made between the sole transport of protons to the outside and the antiport , where the protons only make up half of the transported particles.

In everyday parlance, the proton pump means the proton potassium pump in stomach cells.

Examples of proton export

• Redox-driven proton pumps can be found in the membranes of the mitochondria and chloroplasts . Its main function is to build up an electrochemical proton gradient (pH gradient), which is required by the ATP synthase to generate chemical energy in the form of ATP . Examples are complex I and complex IV of the respiratory chain in mitochondria. The complex II is not a proton pump. Here the proton gradient is built up via the Q cycle .

• The light-driven proton pump bacteriorhodopsin is found in the membranes of halobacteria . Another example of light-driven proton pumps would be Acetabularia - Rhodopsin (in Acetabularia acetabulum )

• Many plants (practically all except grasses) pump protons into the rhizosphere while consuming ATP in order to make iron (III) ions, which are bound there in the form of insoluble hydroxides , available and then to take them up. The proton pumps are located in the membranes of the outermost root cells, the rhizodermis .

• In the "sealed zone" of the osteoclasts there are also proton pumps that create an acidic environment, which dissolves the bone.

Examples of antiport

• The proton potassium pump (H ⁺ / K ⁺ -ATPase) is found in the parietal cells in the stomach .

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1. ↑ David Ewers, Acetabularia-Rhodopsin, a light-driven proton pump from an autotrophic eukaryote, Göttingen 2005

See also

• Proton pump inhibitors

Web links

• RUB researchers decipher new functions of protein-bound water molecules . Press release from June 30, 2011