Primary structure, functional characteristics and tissue expression pattern of human ATA2, a subtype of amino acid transport system A

Biochim Biophys Acta. 2000 Jul 31;1467(1):1-6. doi: 10.1016/s0005-2736(00)00252-2.


We report here on the primary structure and functional characteristics of the protein responsible for the system A amino acid transport activity that is known to be expressed in most human tissues. This transporter, designated ATA2 for amino acid transporter A2, was cloned from the human hepatoma cell line HepG2. Human ATA2 (hATA2) consists of 506 amino acids and exhibits a high degree of homology to rat ATA2. hATA2-specific mRNA is ubiquitously expressed in human tissues. When expressed in mammalian cells, hATA2 mediates Na+-dependent transport of alpha-(methylamino)isobutyric acid, a specific model substrate for system A. The transporter is specific for neutral amino acids. It is pH-sensitive and Li+-intolerant. The Na+:amino acid stoichiometry is 1:1.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Amino Acid Transport Systems
  • Biological Transport
  • Carbon Radioisotopes
  • Carrier Proteins / biosynthesis
  • Carrier Proteins / chemistry
  • Carrier Proteins / physiology*
  • Cloning, Molecular
  • Gene Expression Regulation
  • Gene Library
  • Humans
  • Molecular Sequence Data
  • RNA, Messenger / analysis
  • Substrate Specificity
  • Transfection
  • Tumor Cells, Cultured
  • beta-Alanine / analogs & derivatives
  • beta-Alanine / physiology


  • Amino Acid Transport Systems
  • Carbon Radioisotopes
  • Carrier Proteins
  • RNA, Messenger
  • beta-Alanine
  • 2,2-dimethyl-beta-alanine