Potassium biological function

The behavior of metals as atoms or ions deeply affects the electrochemical reactions they undergo, and similarly affects the metabolism of plants and animals. Iron, copper, cobalt, potassium, and sodium are examples of metals that are essential to biological function. Some metals such as cadmium, mercury, lead, barium, chromium, and beryllium are highly toxic. 

Humans and other vertebrates must have sodium and potassium in their diets because many biological functions are controlled by sodium and potassium ions. Potassium ions are the most common positive ions within cells. Sodium ions are the most common positive ions in the fluid that surrounds cells. When a nerve cell is stimulated, sodium ions flow into the cell and potassium ions flow out. This flow of ions across the cell membrane carries the nerve impulse along the cell. After the impulse passes, a compound attached to the cell membrane uses energy to move the ions back across the membrane so that they are in position for the next impulse. 

Sodium and potassium are the most abundant alkali metals. Many biological functions are controlled by sodium and potassium ions. 

The polyether nonactin (174) is an antibiotic tetralide produced by the Streptomyces family of microorganisms. From a biological point of view, nonactin and the other compounds in this family of tetrameric lactones have the ablility to strongly complex potassium ion and to facilitate the transport of potassium across membranes by providing a lipophilic shell. Ion transport has been shown to have a strong influence on important biological functions such as oxidative phosphorylation and mitochondrial respiration. 

Calcium-activated potassium channels. Calcium-activated potassium channels are important membrane proteins associated with a wide range of biological functions including smooth muscle neurotransmitter release, proliferation of white blood cells, red blood cell size, and many more. This channels functions by pumping out K ions when they detect Ca ions, resulting in hyperpolarisation due to subsequent calcium channel deactivation. 

Weber, L. A., Hickey, E.D., Nuss, D.L. Bayloni, C. (1977). 5 -terminal 7-methyl-guanosine and messenger RNA function influence of potassium concentration on translation in vitro. Journal of Biological Chemistry, 252, 4007-10. 

Dauplais, M., Lecoq, A., Song, J., Cotton, J., Jamin, N., Gilquin, B., Roumestand, C., Vita, C., de Medeiros, C.L.C., Rowan, E.G., Harvey, A.L. and Menez, A. (1997) On the convergent evolution of animal toxins. Conservation of a diad of functional residues in potassium channel-blocking toxins with unrelated structures. Journal of Biological Chemistry 272, 4302 309. 

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