Excitatory amino acid transporter 5 is widely expressed in peripheral tissues

Eur J Histochem. 2013 Mar 12;57(1):e11. doi: 10.4081/ejh.2013.e11.

Abstract

It is routinely stated in the literature that Excitatory Amino Acid Transporter 5 (EAAT5) is a retina-specific glutamate transporter. EAAT5 is expressed by retinal photoreceptors and bipolar cells, where it serves as a slow transporter and as an inhibitory glutamate receptor, the latter role is due to the gating of a large chloride conductance. The dogma of an exclusively retinal distribution has arisen because Northern blot analyses have previously shown only modest hybridisation in non-retinal tissues. Others have re-interpreted this as indicating that EAAT5 was only present in retinal tissues. However, this view appears to be erroneous; recent evidence demonstrating abundant expression of EAAT5 in rat testis prompted us to re-examine this dogma. A new antibody was developed to an intracellular loop region of rat EAAT5. This new tool, in concert with RT-PCR and sequencing, demonstrated that EAAT5 is widely distributed at the mRNA and protein levels in many non-nervous tissues including liver, kidney, intestine, heart, lung, and skeletal muscle. We conclude that EAAT5 is a widely distributed protein. Whether it functions in all locations as a glutamate transporter, or mainly as a glutamate-gated chloride conductance, remains to be determined.

MeSH terms

  • Animals
  • Excitatory Amino Acid Transporter 5 / biosynthesis*
  • Gene Expression Regulation / physiology*
  • Kidney / metabolism*
  • Liver / metabolism*
  • Lung / metabolism*
  • Muscle, Skeletal / metabolism*
  • Myocardium / metabolism*
  • Organ Specificity / physiology
  • RNA, Messenger / biosynthesis
  • Rats
  • Reverse Transcriptase Polymerase Chain Reaction

Substances

  • Excitatory Amino Acid Transporter 5
  • RNA, Messenger
  • Slc1a7 protein, rat