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glutamate receptor, ionotropic kainate 1; glutamate receptor 5; GluR-5; GluR5; excitatory amino acid receptor 3; EAA3 (GRIK1, GLUR5)
Function:
- non NMDA 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
- receptor binds domoate > kainate > L-glutamate = quisqualate > CNQX = DNQX > AMPA > dihydrokainate > NMDA
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=2 additional isoforms seem to exist
Expression:
- most abundant in the cerebellum & the suprachiasmatic nuclei (SCN) of the hypothalamus
- expressed in motor neurons
Pathology:
- mutations in GluR5 may be associated with familial ALS [2]
Genetics:
- RNA editing:
a) modified positions=636, partially edited
b) the unedited version (Q) assembles into a functional kainate-gated homomeric channel, whereas the edited version (R) is unable to produce channel activity when expressed alone
c) both edited & unedited versions can form functional channels with GRIK4 & GRIK5 (putative)
General
glutamate receptor beta
glycoprotein
phosphoprotein
Properties
SIZE: entity length = 918 aa
MW = 104 kD
COMPARTMENT: plasma membrane
MOTIF: exoplasmic domain {31-576}
MOTIF: signal sequence {1-30}
N-glycosylation site {N68}
N-glycosylation site {N74}
N-glycosylation site {N276}
N-glycosylation site {N379}
N-glycosylation site {N428}
N-glycosylation site {N439}
N-glycosylation site {N446}
Glutamate binding {531-533}
binding site
SITE: 538-538
FOR-BINDING-OF: Glutamate
N-glycosylation site {N561}
transmembrane domain {577-597}
cytoplasmic loop {598-653}
transmembrane domain {654-674}
exoplasmic loop {675-834}
MOTIF: Glutamate binding {704-705}
Ser phosphorylation site {S725}
binding site
SITE: 753-753
FOR-BINDING-OF: Glutamate
Thr phosphorylation site {T761}
transmembrane domain {835-855}
cytoplasmic domain {856-918}
Database Correlations
OMIM 138245
UniProt P39086
PFAM correlations
Entrez Gene 2897
Kegg hsa:2897
References
- UniProt :accession P39086
- Eubanks JH, Puranam RS, Kleckner NW, Bettler B, Heinemann SF,
McNamara JO.
The gene encoding the glutamate receptor subunit GluR5 is
located on human chromosome 21q21.1-22.1 in the vicinity of
the gene for familial amyotrophic lateral sclerosis.
Proc Natl Acad Sci U S A. 1993 Jan 1;90(1):178-82.
PMID: 8419920