TY - JOUR
T1 - Structure and function of ATA3, a new subtype of amino acid transport system A, primarily expressed in the liver and skeletal muscle
AU - Sugawara, Mitsuru
AU - Nakanishi, Takeo
AU - Fei, You Jun
AU - Martindale, Robert G.
AU - Ganapathy, Malliga E.
AU - Leibach, Frederick H.
AU - Ganapathy, Vadivel
PY - 2000/12/20
Y1 - 2000/12/20
N2 - 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-[14C](methylamino)isobutyric acid and [3H]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 K0.5 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. (C) 2000 Elsevier Science B.V.
AB - 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-[14C](methylamino)isobutyric acid and [3H]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 K0.5 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. (C) 2000 Elsevier Science B.V.
KW - Amino acid transporter A3
KW - Electrophysiology
KW - Liver
KW - Rat
KW - Skeletal muscle
KW - System A
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U2 - 10.1016/S0005-2736(00)00349-7
DO - 10.1016/S0005-2736(00)00349-7
M3 - Article
C2 - 11118514
AN - SCOPUS:0034695035
SN - 0005-2736
VL - 1509
SP - 7
EP - 13
JO - Biochimica et Biophysica Acta - Biomembranes
JF - Biochimica et Biophysica Acta - Biomembranes
IS - 1-2
ER -