Structure and function of ATA3, a new subtype of amino acid transport system A, primarily expressed in the liver and skeletal muscle.

摘要: Abstract 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 known as ATA1 and ATA2. We cloned a third transporter is able to A-specific substrate. This new transporter, from rat skeletal muscle designated rATA3, consists 547 acids has high degree homology (47% identity) ATA2 (57% identity). rATA3 mRNA present only in liver muscle. When expressed Xenopus laevis oocytes, mediates α-[ 14 C](methylamino)isobutyric [ 3 H]alanine. With two-microelectrode voltage clamp technique, we shown exposure rATA3-expressing oocytes neutral, short-chain aliphatic induces inward currents. The acid-induced current Na + -dependent pH-dependent. Analysis currents with alanine K 0.5 (i.e., concentration yielding half-maximal current) 4.2±0.1 mM :alanine stoichiometry 1:1.