Evidence for hybrid NMDA/kainate receptors from protein reconstitution studies and expression of vertebrate CNS RNAs in Xenopus oocytes.
1. A review is presented of recent advances in glutamate receptor research with particular emphasis on studies which show that some glutamate receptors in the central nervous systems (CNS) of Xenopus and rat contain a mixture of N-methyl-D-aspartate-sensitive and kainate-sensitive subunits. 2. Protein isolated from Xenopus CNS using a domoic acid affinity column exhibits complex pharmacological properties. It binds both [3H]kainate and [3H]glycine: the binding of the latter is strychnine-insensitive. 3. When reconstituted into lipid bilayers, channels gated by kainate and NMDA can be elicited and the properties of these channels are similar to those gated by kainate receptors and NMDA receptors, respectively, in studies of vertebrate central neurones in situ. 4. The protein can be fractionated into two components; one of which is sensitive only to kainate and AMPA, the other exhibiting sensitivity to both kainate and NMDA. 5. When RNA isolated from Xenopus and rat CNS is injected into Xenopus oocytes, responses to kainate and NMDA can be seen within 2-3 days. The responses to co-application of these agonists support the contention that some of the glutamate receptors expressed in oocytes contain both kainate-sensitive and NMDA-sensitive subunits.
Department of Life Science, University of Nottingham, U.K.
P N
PN
Usherwood
E A
EA
Barnard
D000818:Animals; D002846:Chromatography, Affinity; D005998:Glycine / Q000378:metabolism; D015640:Ion Channel Gating; D007608:Kainic Acid / Q000378:metabolism* / Q000494:pharmacology; D016202:N-Methylaspartate / Q000378:metabolism* / Q000494:pharmacology; D009865:Oocytes / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017470:Receptors, Glutamate / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
D005998:Glycine; D007608:Kainic Acid; D016202:N-Methylaspartate; D012333:RNA, Messenger; D017470:Receptors, Glutamate; D018092:Kainic Acid Receptors; D016194:Receptors, N-Methyl-D-Aspartate