Molecular characterization of the human EAA5 (GluR7) receptor: a high-affinity kainate receptor with novel potential RNA editing sites

Recept Channels. 1994;2(4):315-26.

Abstract

Several cDNA clones encoding EAA5 receptor polypeptides were isolated from a human fetal brain library. The EAA5 cDNAs demonstrated an 88.7-90.1% nucleotide identity with rat GluR7 cDNAs. The nucleotide sequence of EAA5 would encode a 919-amino acid protein, that has a 97.7-98.9% identity with the rat GluR7 receptor. Two variation of the EAA5 cDNA were identified which result in amino acid substitutions in the predicted extracellular amino-terminal region; Ser310-->Ala and Arg352-->Gln. These variations can be attributed to RNA editing involving T-->G and G-->A substitutions. Both the location (with respect to glutamate receptors), and the nucleotides involved, in this putative RNA editing are novel and may therefore involve novel mechanisms. Ligand binding studies with membranes of transfected COS-1 cells expressing EAA5 polypeptides demonstrate a rank order of ligand affinity similar to that observed with the rat GluR7 receptor, and a dissociation constant for kainate (2.72 +/- 0.12 nM (n = 3)) that is approximately 20- to 30-fold higher than that observed for the rat GluR7 receptor. All of the ligands tested had a higher affinity for the human EAA5 receptor as compared to the rat GluR7 receptor. This report provides another example of pharmacological differences for similar receptors across species.

Publication types

  • Comparative Study

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Binding Sites
  • Binding, Competitive
  • Brain / metabolism*
  • Cell Line
  • Chlorocebus aethiops
  • Cloning, Molecular
  • DNA, Complementary / analysis
  • Gene Expression
  • Gene Library
  • Humans
  • Kainic Acid / metabolism
  • Kainic Acid / pharmacology
  • Kidney
  • Kinetics
  • Membrane Potentials / drug effects
  • Molecular Sequence Data
  • Patch-Clamp Techniques
  • Rats
  • Receptors, Kainic Acid / biosynthesis*
  • Receptors, Kainic Acid / chemistry*
  • Receptors, Kainic Acid / genetics
  • Receptors, Kainic Acid / metabolism
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / metabolism
  • Sequence Homology, Amino Acid
  • Sequence Homology, Nucleic Acid
  • Transfection

Substances

  • DNA, Complementary
  • GluK3 kainate receptor
  • Receptors, Kainic Acid
  • Recombinant Proteins
  • Kainic Acid

Associated data

  • GENBANK/U16127
  • GENBANK/U16128