Ion pump (biology)

In biology, an ion transporter (or ion pump) is a transmembrane protein that moves ions across a plasma membrane against their concentration gradient through active transport. These primary transporters are enzymes that convert energy from various sources—including Adenosine triphosphate(ATP), sunlight, and other Redox reactions—to potential energy stored in an electrochemical gradient. This potential energy is then used by secondary transporters, including ion carriers and ion channels, to drive vital cellular processes, such as ATP synthesis.

Ion transporters are classified as a super family of transporters that contain 12 families of transporters. These families are part of the Transport Classification (TC) system that is used by the International Union of Biochemistry and Molecular Biology (IUBMB) and are grouped according to characteristics such as the substrates being transported, the transport mechanism, the energy source used, and also by comparing the DNA sequences making up each protein. The most important unifying factor being the charged nature of the substrate which indicates the transport of an ion and not a neutral species.

Ion transporters differ significantly from ion channels. An electrochemical gradient or concentration gradient is a difference in concentration of a chemical molecule or ion in two separate areas. At equilibrium the concentrations of the ion in both areas will be equal, so if there is a difference in concentration the ions will seek to flow "down" the concentration gradient or from a high concentration to low concentration. Ion channels allows the specific ions that will fit into the channel to flow down their concentration gradient, equalizing the concentrations on either side of the cell membrane. Ion channels accomplish this via facilitated diffusion which is a type of passive transport. In contrast, ion transporters perform active transport by moving ions against their concentration gradient. Using energy sources such as ATP, ion transporters are able to move ions against their concentration gradient which can then be used by secondary transporters or other proteins as a source of energy.

...
Wikipedia