Transcripción
The aquaporines (AQP) are a class of Protéine S membrane which form permeable pores with the water molecules in the biological membranes.
The aquaporines allow the drainage duct on both sides of the membrane while preventing the ions from penetrating in the cell.
The aquaporines consist of 6 propellers alpha which fit in double-layered the lipidic constituent one of the membrane. These 6 propellers are connected by a loop of amino-acid whose 3 particularly important is in the medium: NPA (NR for asparagine, P for proline and has as an alanine). It is vis-a-vis this reason NPA that the break of the H+ ions can be done.
The aquaporines are independent tetramers, i.e. they are made up of 4 monomers able to transport the molecules of H2O individually. One could compare them with a sand glass which would make pass to molecules.
The aquaporines strongly increase the permeability of the membranes to water. They are essential with the activity of bodies such as the kidney (3 different kinds of aquaporines), and are implied in biological functions such as the tears.
Today, approximately 500 aquaporines were discovered as well in the vegetable kingdom as animal including 12 at the Homme.
A genetic defect in the expression of these proteins was associated with certain human diseases.
Let us quote for example the AQP2 which transferred is responsible on the level for the kidney of a severe dehydration. This AQP2, if it is present in excess, is also responsible for edema (cardiac failure). The AQP0, as for it is responsible for the cataract if it is transferred.
The aquaporines were discovered by Peter Agre in 1992 by injecting ARNm of protein in an egg of xénope. In 2003 this one received the Nobel Prize of chemistry for its work.
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