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Publication Abstract from PubMed

AvGluR1, a glutamate receptor ion channel from the primitive eukaryote Adineta vaga, is activated by alanine, cysteine, methionine, and phenylalanine, which produce lectin-sensitive desensitizing responses like those to glutamate, aspartate, and serine. AvGluR1 LBD crystal structures reveal an unusual scheme for binding dissimilar ligands that may be utilized by distantly related odorant/chemosensory receptors. Arginine residues in domain 2 coordinate the gamma-carboxyl group of glutamate, whereas in the alanine, methionine, and serine complexes a chloride ion acts as a surrogate ligand, replacing the gamma-carboxyl group. Removal of Cl lowers affinity for these ligands but not for glutamate or aspartate nor for phenylalanine, which occludes the anion binding site and binds with low affinity. AvGluR1 LBD crystal structures and sedimentation analysis also provide insights into the evolutionary link between prokaryotic and eukaryotic iGluRs and reveal features unique to both classes, emphasizing the need for additional structure-based studies on iGluR-ligand interactions.

Anions Mediate Ligand Binding in Adineta vaga Glutamate Receptor Ion Channels.,Lomash S, Chittori S, Brown P, Mayer ML Structure. 2013 Mar 5;21(3):414-25. doi: 10.1016/j.str.2013.01.006. Epub 2013 Feb, 21. PMID:23434404^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.