The KA-2 subunit of excitatory amino acid receptors shows widespread expression in brain and forms ion channels with distantly related subunits.
A new ionotropic glutamate receptor subunit termed KA-2, cloned from rat brain cDNA, exhibits high affinity for [3H]kainate (KD approximately 15 nM). KA-2 mRNA is widely expressed in embryonic and adult brain. Homomeric KA-2 expression does not generate agonist-sensitive channels, but currents are observed when KA-2 is coexpressed with GluR5 or GluR6 subunits. Specifically, coexpression of GluR5(R) and KA-2 produces channel activity, whereas homomeric expression of either subunit does not. Currents through heteromeric GluR5(Q)/KA-2 channels show more rapid desensitization and different current-voltage relations when compared with GluR5(Q) currents. GluR6/KA-2 channels are gated by AMPA, which fails to gate homomeric GluR6 receptor channels. These results suggest possible in vivo partnership relations for high affinity kainate receptors.
Herb
A
A
Center for Molecular Biology, Heidelberg University, Germany.
Burnashev
N
N
Werner
P
P
Sakmann
B
B
Wisden
W
W
Seeburg
P H
PH
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000502:physiology*; D003001:Cloning, Molecular; D015870:Gene Expression; D007473:Ion Channels / Q000235:genetics / Q000648:ultrastructure*; D008024:Ligands; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D015345:Oligonucleotide Probes / Q000737:chemistry; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017470:Receptors, Glutamate; D018092:Kainic Acid Receptors; D017981:Receptors, Neurotransmitter / Q000235:genetics / Q000502:physiology*; D016415:Sequence Alignment
D007473:Ion Channels; D008024:Ligands; D046911:Macromolecular Substances; D015345:Oligonucleotide Probes; D012333:RNA, Messenger; D017470:Receptors, Glutamate; D018092:Kainic Acid Receptors; D017981:Receptors, Neurotransmitter