Human cationic amino acid transporter hCAT-3 is preferentially expressed in peripheral tissues

Biochemistry. 2001 Oct 16;40(41):12387-94. doi: 10.1021/bi011345c.


At least five distinct carrier proteins form the family of mammalian cationic amino acid transporters (CATs). We have cloned a cDNA containing the complete coding region of human CAT-3. hCAT-3 is glycosylated and localized to the plasma membrane. Transport studies in Xenopus laevis oocytes revealed that hCAT-3 is selective for cationic L-amino acids and exhibits a maximal transport activity similar to other CAT proteins. The apparent substrate affinity and sensitivity to trans-stimulation of hCAT-3 resembles most closely hCAT-2B. This is in contrast to rat and murine CAT-3 proteins that have been reported to display a very low activity and to be inhibited by neutral and anionic L-amino acids as well as D-arginine (Hosokawa, H., et al. (1997) J. Biol. Chem. 272, 8717-8722; Ito, K., and Groudine, M. (1997) J. Biol. Chem. 272, 26780-26786). Also, in adult rat and mouse, CAT-3 has been found exclusively in central neurons. Human CAT-3 expression is not restricted to the brain, in fact, by far the highest expression was found in thymus. Also in other peripheral tissues, hCAT-3 expression was equal to or higher than in most brain regions, suggesting that hCAT-3 is not a neuron-specific transporter.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Amino Acid Transport Systems, Basic
  • Animals
  • Base Sequence
  • Brain / metabolism
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism*
  • Cell Line
  • DNA, Complementary / genetics
  • DNA, Complementary / isolation & purification
  • Female
  • Gene Expression
  • Humans
  • In Vitro Techniques
  • Male
  • Membrane Proteins / genetics*
  • Membrane Proteins / metabolism*
  • Mice
  • Oocytes / metabolism
  • Rats
  • Thymus Gland / metabolism
  • Tissue Distribution
  • Xenopus laevis


  • Amino Acid Transport Systems, Basic
  • Carrier Proteins
  • DNA, Complementary
  • Membrane Proteins