title: Excitatory amino acid transporter 5 is widely expressed in peripheral tissues.
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.
authors.affiliation: UQ Centre for Clinical Research, The University of Queensland, Brisbane, QLD, Australia, Queensland, Australia. aven.lee@uq.edu.au
authors.forename: A
authors.initials: A
authors.lastname: Lee
authors.forename: A R
authors.initials: AR
authors.lastname: Anderson
authors.forename: M
authors.initials: M
authors.lastname: Stevens
authors.forename: S
authors.initials: S
authors.lastname: Beasley
authors.forename: N L
authors.initials: NL
authors.lastname: Barnett
authors.forename: D V
authors.initials: DV
authors.lastname: Pow
mesh_terms: D000818:Animals; D050582:Excitatory Amino Acid Transporter 5 / Q000096:biosynthesis*; D005786:Gene Expression Regulation / Q000502:physiology*; D007668:Kidney / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008168:Lung / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D009928:Organ Specificity / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D050582:Excitatory Amino Acid Transporter 5; D012333:RNA, Messenger; C484554:Slc1a7 protein, rat
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