Proton pump
As proton pump are in biochemistry and physiology generally referred transmembrane proteins protons across a biological membrane against an electrochemical gradient, transport. There is a large and diverse group of proteins. A rough distinction between the sole transport of protons to the outside and anti- port, where the protons represent only one half of the transported particles.
In everyday parlance, is meant in gastric cells with proton pump, the proton- potassium pump.
Examples of the proton- export
- In the membranes of mitochondria and chloroplasts redoxgetriebene proton pump are provided. Their main function is to build an electrochemical proton gradient (pH gradient), which is required by the ATP synthase to produce chemical energy in the form of ATP. Examples are the complex I and complex IV of the respiratory chain in mitochondria. Complex II is not a proton pump. Here the proton gradient across the Q- cycle is established.
- In the membranes of halobacteria to find the light-driven proton pump bacteriorhodopsin. Another example of light-driven proton pump would Acetabularia rhodopsin ( in Acetabularia acetabulum )
- Many plants ( virtually all but the grasses) pump with consumption of ATP protons into the rhizosphere to make iron (III ) ions, which are bound as insoluble hydroxides available and then take. The proton pumps are located in the membranes of the outermost root cells, the rhizodermis.
- In the "sealed zone" of osteoclasts also are proton pumps that produce an acidic environment, so that the bone is dissolved.
Examples of antiport
- In the parietal cells in the stomach we find the proton- potassium pump (H / K - ATPase).