Comparison of solubilised kainate and alpha-amino-3-hydroxy-5- methylisoxazolepropionate binding sites in chick cerebellum.
[3H]Kainate bound to chick cerebellar membranes with a KD of 0.6 microM and with an exceptionally high Bmax of 165 pmol/mg of protein. In octylglucoside-solubilised extracts, the affinity of [3H]kainate was reduced (KD = 2.7 microM), but the Bmax was relatively unchanged (130 pmol/mg of protein). The rank potency of competitive ligands was domoate greater than kainate greater than 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) greater than glutamate. Binding sites for alpha-[3H]amino-3- hydroxy-5-methylisoxazolepropionate ([3H]AMPA) were much less abundant, with KD and Bmax values in membranes of 86 nM and 1 pmol/mg of protein, respectively. The affinity of [3H]AMPA binding was also reduced on solubilisation (KD = 465 nM), but there was an increase in the Bmax (1.7 pmol/mg of protein). Quisqualate and CNQX were the most effective displacers of [3H]AMPA binding, but kainate was also a relatively potent inhibitor. However, in contrast to the displacement profile for [3H]kainate, domoate was markedly less potent than kainate at displacing [3H]AMPA. These results suggest that [3H]AMPA binds to a small subset of the kainate sites that, unlike the majority of the [3H]kainate binding protein, which has been reported to be located in the Bergmann glia, may represent neuronal unitary non-N-methyl-D-aspartate receptors.
Henley
J M
JM
Molecular Neurobiology Unit, MRC Centre, Cambridge, England.
Barnard
E A
EA
D000818:Animals; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism; D002531:Cerebellum / Q000378:metabolism*; D002645:Chickens; D005960:Glucosides; D007051:Ibotenic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D007608:Kainic Acid / Q000031:analogs & derivatives / Q000378:metabolism*; D018091:Receptors, AMPA; D018092:Kainic Acid Receptors; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D012995:Solubility; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
D005960:Glucosides; D007051:Ibotenic Acid; D007608:Kainic Acid; D018091:Receptors, AMPA; D018092:Kainic Acid Receptors; D017981:Receptors, Neurotransmitter; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; C018619:octyl-beta-D-glucoside; C012301:domoic acid