Disease:Defects in GRIK2 are the cause of autosomal recessive mental retardation type 6 (MRT6) [MIM:611092]. Patients display mild to severe mental retardation and psychomotor development delay in early childhood. Patients do not have neurologic problems, congenital malformations, or facial dysmorphism. Body height, weight, and head circumference are normal in all patients. Magnetic resonance imaging (MRI) scan, reveals no morphologic abnormalities.,Function:Ionotropic glutamate receptor. L-glutamate acts as an excitatory neurotransmitter at many synapses in the central nervous system. Binding of the excitatory neurotransmitter L-glutamate induces a conformation change, leading to the opening of the cation channel, and thereby converts the chemical signal to an electrical impulse. The receptor then desensitizes rapidly and 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.,miscellaneous:The postsynaptic actions of Glu are mediated by a variety of receptors that are named according to their selective agonists. This receptor binds domoate > kainate > quisqualate > 6-cyano-7-nitroquinoxaline-2,3-dione > L-glutamate = 6,7-dinitroquinoxaline-2,3-dione > dihydrokainate.,PTM:Sumoylation mediates kainate receptor-mediated endocytosis and regulates synaptic transmission. Sumoylation is enhanced by PIAS3 and desumoylated by SENP1.,RNA editing:Partially edited. The presence of Gln at position 621 (non-edited) determines channels with low calcium permeability, whereas Arg (edited) determines a higher calcium permeability especially if the preceding sites are fully edited. This 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).,similarity:Belongs to the glutamate-gated ion channel (TC 1.A.10) family.,subunit:Homotetramer or heterotetramer of pore-forming glutamate receptor subunits. Tetramers may be formed by the dimerization of dimers (Probable). 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 (By similarity). Interacts with DLG4.,tissue specificity:Expression is higher in cerebellum than in cerebral cortex.,
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