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Ion transport versus gas conduction: function of AMT/Rh-type proteins.

Ludewig, Uwe :
Ion transport versus gas conduction: function of AMT/Rh-type proteins.
In: Transfusion clinique et biologique : journal de la Société française de transfusion sanguine, 13 (1-2) pp. 111-116. ISSN 1246-7820
[Article] , (2006)

Abstract

Although lipid membranes exhibit some permeability to the weak base NH3, organisms have developed specialized proteins that increase and regulate the NH3 fluxes across cellular membranes. In humans, the Rh glycoproteins, such as the erythrocyte-specific RhAG and the liver and kidney homologs RhBG and RhCG, are involved in the passage of NH3. Rh glycoproteins have distant relatives, called ammonium transporters (AMTs), in archae and bacteria. The crystal structures of AMTs show that the proteins are homo-trimers and that the center of each monomer forms a pore. AMT/Rh proteins have also been identified in plants. In contrast to the human Rh glycoproteins, these AMTs specifically transport NH4+ or co-transport NH3/H+. Hence, they can transport against NH3 gradients. The molecular determinants for the different transport mechanisms within proteins of the same family are currently unclear. The functional differences between AMT/Rh transporters are likely to be an evolutionary adaptation to different ammonium and nitrogen requirements in bacteria, plants and animals.

Item Type: Article
Erschienen: 2006
Creators: Ludewig, Uwe
Title: Ion transport versus gas conduction: function of AMT/Rh-type proteins.
Language: English
Abstract:

Although lipid membranes exhibit some permeability to the weak base NH3, organisms have developed specialized proteins that increase and regulate the NH3 fluxes across cellular membranes. In humans, the Rh glycoproteins, such as the erythrocyte-specific RhAG and the liver and kidney homologs RhBG and RhCG, are involved in the passage of NH3. Rh glycoproteins have distant relatives, called ammonium transporters (AMTs), in archae and bacteria. The crystal structures of AMTs show that the proteins are homo-trimers and that the center of each monomer forms a pore. AMT/Rh proteins have also been identified in plants. In contrast to the human Rh glycoproteins, these AMTs specifically transport NH4+ or co-transport NH3/H+. Hence, they can transport against NH3 gradients. The molecular determinants for the different transport mechanisms within proteins of the same family are currently unclear. The functional differences between AMT/Rh transporters are likely to be an evolutionary adaptation to different ammonium and nitrogen requirements in bacteria, plants and animals.

Journal or Publication Title: Transfusion clinique et biologique : journal de la Société française de transfusion sanguine
Volume: 13
Number: 1-2
Divisions: 10 Department of Biology > Plant Nutrition and Biomass
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10 Department of Biology
Date Deposited: 16 Mar 2010 08:58
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