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glutamate receptor, ionotropic kainate 2; glutamate receptor 6; GluR-6; GluR6; excitatory amino acid receptor 4; EAA4 (GRIK2, GLUR6)
Function:
- ionotropic glutamate receptor subunit
- binding of the excitatory neurotransmitter L-glutamate induces a conformation change, leading to the opening of the cation channel, & thereby converts the chemical signal to an electrical impulse
- the receptor then desensitizes rapidly & enters a transient inactive state, characterized by the presence of bound agonist
- may be involved in the transmission of light information from the retina to the hypothalamus
- assembles into a kainate-gated homomeric channel that does not bind AMPA
- GRIK2 associated to GRIK5 forms functional channels that can be gated by AMPA (putative)
- interacts with DLG4
- receptor binds domoate > kainate > quisqualate > 6-cyano-7-nitroquinoxaline-2,3-dione > L-glutamate = 6,7-dinitroquinoxaline-2,3-dione > dihydrokainate
Structure:
- homotetramer or heterotetramer of pore-forming glutamate receptor subunits
- tetramers may be formed by the dimerization of dimers (probable)
- belongs to the glutamate-gated ion channel (TC 1.A.10) family
Compartment:
- cell membrane
- cell junction, synapse, postsynaptic cell membrane
Alternative splicing: named isoforms=5
Expression:
- expression is higher in cerebellum than in cerebral cortex
Pathology:
- defects in GRIK2 are the cause of: autosomal recessive mental retardation type 6
Genetics:
- RNA editing
a) modified positions=567, 571, 621
b) partially edited
c) the presence of Gln at position 621 (non-edited) determines channels with low Ca+2 permeability, whereas Arg (edited) determines a higher Ca+2 permeability especially if the preceding sites are fully edited
d) receptor is nearly completely edited in all gray matter structures (90% of the receptors), whereas much less edited in the white matter (10% of the receptors)
General
glutamate receptor beta
glycoprotein
Properties
SIZE: entity length = 908 aa
MW = 103 kD
COMPARTMENT: plasma membrane
MOTIF: exoplasmic domain {1-561}
MOTIF: signal sequence {1-31}
N-glycosylation site {N67}
N-glycosylation site {N73}
N-glycosylation site {N275}
N-glycosylation site {N378}
N-glycosylation site {N412}
N-glycosylation site {N423}
N-glycosylation site {N430}
Glutamate binding {516-518}
binding site
SITE: 523-523
FOR-BINDING-OF: Glutamate
N-glycosylation site {N546}
transmembrane domain {562-582}
cytoplasmic loop {583-635}
transmembrane domain {636-656}
exoplasmic loop {657-819}
MOTIF: Glutamate binding {689-690}
binding site
SITE: 738-738
FOR-BINDING-OF: Glutamate
transmembrane domain {820-840}
cytoplasmic domain {841-908}
Database Correlations
OMIM correlations
UniProt Q13002
PFAM correlations
Entrez Gene 2898
Kegg hsa:2898
References
UniProt :accession Q13002