A ligand binding study of the interactions of guanine nucleotides with non-NMDA receptors.
The interactions of guanine nucleotides, and particularly GTP, with the [3H]-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) and [3H]-kainate (KA) binding sites present on brain membranes was studied, using the ligand binding methodology and Scatchard analysis, in order to establish the competitive/non competitive nature of the interaction and determine whether guanine nucleotides, KA and AMPA share common binding sites. GTP was found to block [3H]-AMPA and [3H]-KA binding to rat cortical membranes with IC50 values of 0.4 mM and 1 mM respectively and the [3H] KA-binding to chick cerebellar membranes with a IC50 value of 20 microM. Scatchard analysis of [3H]-KA binding performed in the absence or presence of 1 mM GTP or 0.25 mM AMPA reveals that the high affinity [3H]-KA binding component is not affected by GTP but blocked in a non competitive fashion by AMPA while the low affinity [3H]-KA binding component is not affected by AMPA but blocked by GTP. Scatchard analysis of [3H]-KA binding to chick cerebellar membranes performed in the absence or presence of 33 microM GTP reveals a single binding site blocked in a competitive fashion by GTP. Scatchard analysis of [3H]-AMPA binding performed in the absence or presence of 0.5 mM GTP or 30 microM KA reveals that the high affinity [3H]-AMPA binding component is affected in a non competitive fashion by both GTP and KA while the low affinity [3H] AMPA binding component is affected in a competitive fashion by both GTP and KA.(ABSTRACT TRUNCATED AT 250 WORDS)
Gorodinsky
A
A
Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Paas
Y
Y
Teichberg
V I
VI
D000818:Animals; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000494:pharmacology*; D006160:Guanosine Triphosphate / Q000494:pharmacology*; D007608:Kainic Acid / Q000378:metabolism; D007700:Kinetics; D008024:Ligands; D008297:Male; D051381:Rats; D018091:Receptors, AMPA / Q000187:drug effects / Q000378:metabolism*; D018092:Kainic Acid Receptors / Q000187:drug effects / Q000378:metabolism*; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000378:metabolism
D006150:Guanine Nucleotides; D006160:Guanosine Triphosphate; D007608:Kainic Acid; D008024:Ligands; D018091:Receptors, AMPA; D018092:Kainic Acid Receptors; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid