[New concepts in anionic and cationic amino acid transport].
In mammalian cells, amino acids are taken up by different transport systems present in the plasma membrane. The transport systems were originally characterized by kinetic and competition studies. However, it was difficult to assign specific amino acids to specific transport systems. With recent advances in molecular biology, it has been possible to identify the specific transporter proteins for specific amino acids. In this review we describe the anionic and cationic amino acid transport systems reported at the molecular level. The anionic amino acids are movilized mainly by the XaG- and Xc- systems which are important in the inactivation of glutamatergic nervous transmission in the brain and for the synthesis of glutathione, respectively. Four isoforms of the XAG- system in the brain belong to the family of Na+ dependent amino acid transporters. Transport systems for cationic amino acids also recognize zwitterionic substrates, and the better characterized systems at the present time are y+, y+L, bo,+ and Bo,+. The regulation of the entrance of cationic amino acid such as arginine, lysine, and ornithine to the cell is important in the biosynthesis of nitric oxide, creatine, carnitine, and polyamines. An inherited defect associated to bo,+ system is cysteinuria.
Avila-Chávez
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E
Departamento de Fisiología de la Nutrición, Instituto Nacional de la Nutrición Salvador Zubirán, México, D.F.
Torres-y-Torres
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N
Tovar-Palacio
A R
AR
D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D000592:Amino Acid Metabolism, Inborn Errors / Q000378:metabolism; D027322:Amino Acid Transport System X-AG; D026923:Amino Acid Transport Systems, Basic; D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism* / Q000493:pharmacokinetics; D000818:Animals; D000838:Anions / Q000378:metabolism; D001692:Biological Transport; D001921:Brain / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002412:Cations / Q000378:metabolism; D003555:Cystinuria / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D051381:Rats
D018528:ATP-Binding Cassette Transporters; D027322:Amino Acid Transport System X-AG; D026923:Amino Acid Transport Systems, Basic; D000596:Amino Acids; D000838:Anions; D002352:Carrier Proteins; D002412:Cations; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; C499489:SLC7A9 protein, human; C499488:Slc7a9 protein, mouse; D018698:Glutamic Acid
Nuevos conocimientos del transporte de aminoácidos aniónicos y catiónicos.