Structure and function of ATA3, a new subtype of amino acid transport system A, primarily expressed in the liver and skeletal muscle
| Autor: | Frederick H. Leibach, Takeo Nakanishi, You Jun Fei, Robert G. Martindale, Malliga E. Ganapathy, Mitsuru Sugawara, Vadivel Ganapathy |
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| Rok vydání: | 2000 |
| Předmět: |
DNA
Complementary Amino Acid Transport Systems Voltage clamp Molecular Sequence Data Xenopus Biophysics Skeletal muscle Biology Biochemistry Isobutyric acid Substrate Specificity chemistry.chemical_compound Xenopus laevis medicine Animals Amino Acid Sequence Cloning Molecular Muscle Skeletal Gene Library Alanine chemistry.chemical_classification Messenger RNA Sequence Homology Amino Acid Amino acid transporter A3 Transporter Cell Biology biology.organism_classification System A Molecular biology Amino acid Rats Electrophysiology medicine.anatomical_structure chemistry Liver Oocytes beta-Alanine Rat Carrier Proteins |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Biomembranes. 1509(1-2):7-13 |
| ISSN: | 0005-2736 |
| DOI: | 10.1016/s0005-2736(00)00349-7 |
| Popis: | To date, two different transporters that are capable of transporting α-(methylamino)isobutyric acid, the specific substrate for amino acid transport system A, have been cloned. These two transporters are known as ATA1 and ATA2. We have cloned a third transporter that is able to transport the system A-specific substrate. This new transporter, cloned from rat skeletal muscle and designated rATA3, consists of 547 amino acids and has a high degree of homology to rat ATA1 (47% identity) and rat ATA2 (57% identity). rATA3 mRNA is present only in the liver and skeletal muscle. When expressed in Xenopus laevis oocytes, rATA3 mediates the transport of α-[ 14 C](methylamino)isobutyric acid and [ 3 H]alanine. With the two-microelectrode voltage clamp technique, we have shown that exposure of rATA3-expressing oocytes to neutral, short-chain aliphatic amino acids induces inward currents. The amino acid-induced current is Na + -dependent and pH-dependent. Analysis of the currents with alanine as the substrate has shown that the K 0.5 for alanine (i.e., concentration of the amino acid yielding half-maximal current) is 4.2±0.1 mM and that the Na + :alanine stoichiometry is 1:1. |
| Databáze: | OpenAIRE |
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