TY - JOUR
T1 - Identification of an extracellular motif involved in the binding of guanine nucleotides by a glutamate receptor
AU - Paas, Yoav
AU - Devillers-Thiéry, Anne
AU - Changeux, Jean Pierre
AU - Medevielle, Francois
AU - Teichberg, Vivian I.
PY - 1996/4/1
Y1 - 1996/4/1
N2 - The chick cerebellar kainate (KA) binding protein (KBP), a member of the family of ionotropic glutamate receptors, harbours a glycine-rich (GxGxxG) motif known to be involved in the binding of ATP and GTP to kinases and G proteins respectively. Here, we report that guanine, but not adenine, nucleotides interact with KBP by inhibiting [3H]KA binding in a competitive-like manner, displaying IC50 values in the micromolar range. To locate the GTP binding site, KBP was photoaffinity labelled with [α-32P]GTP. The reaction was blocked by KA, glutamate, 6-cyano-7-nitroquinoxaline-2,3-dione and antibodies raised against a peptide containing the glycine-rich motif. Site-directed mutagenesis of residues K72 and Y73 within the glycine-rich motif followed by the expression of the KBP mutants at the surface of HEK 293 cells showed a decrease in GTP binding affinity by factors of 10 and 100 respectively. The binding of [3H]KA to the K72A/T KBP mutants was not affected but binding to the Y73I KBP mutant was decreased by a factor of 10. Accordingly, we propose that the glycine-rich motif of KBP forms part of a guanine nucleotide binding site. We further suggest that the glycine-rich motif is the binding site at which guanine nucleotides inhibit the glutamate-mediated responses of various members of the subfamily of glutamate ionotropic receptors.
AB - The chick cerebellar kainate (KA) binding protein (KBP), a member of the family of ionotropic glutamate receptors, harbours a glycine-rich (GxGxxG) motif known to be involved in the binding of ATP and GTP to kinases and G proteins respectively. Here, we report that guanine, but not adenine, nucleotides interact with KBP by inhibiting [3H]KA binding in a competitive-like manner, displaying IC50 values in the micromolar range. To locate the GTP binding site, KBP was photoaffinity labelled with [α-32P]GTP. The reaction was blocked by KA, glutamate, 6-cyano-7-nitroquinoxaline-2,3-dione and antibodies raised against a peptide containing the glycine-rich motif. Site-directed mutagenesis of residues K72 and Y73 within the glycine-rich motif followed by the expression of the KBP mutants at the surface of HEK 293 cells showed a decrease in GTP binding affinity by factors of 10 and 100 respectively. The binding of [3H]KA to the K72A/T KBP mutants was not affected but binding to the Y73I KBP mutant was decreased by a factor of 10. Accordingly, we propose that the glycine-rich motif of KBP forms part of a guanine nucleotide binding site. We further suggest that the glycine-rich motif is the binding site at which guanine nucleotides inhibit the glutamate-mediated responses of various members of the subfamily of glutamate ionotropic receptors.
KW - Glutamate receptors
KW - Guanine nucleotide binding site
KW - Kainate binding protein
KW - Photoaffinity labelling
UR - http://www.scopus.com/inward/record.url?scp=0029927717&partnerID=8YFLogxK
U2 - 10.1002/j.1460-2075.1996.tb00499.x
DO - 10.1002/j.1460-2075.1996.tb00499.x
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C2 - 8612578
AN - SCOPUS:0029927717
SN - 0261-4189
VL - 15
SP - 1548
EP - 1556
JO - EMBO Journal
JF - EMBO Journal
IS - 7
ER -