Inward rectifier K+ channel Kir2.3 is localized at the postsynaptic membrane of excitatory synapses.
Classical inwardly rectifying K+ channels (Kir2.0) are responsible for maintaining the resting membrane potential near the K+ equilibrium potential in various cells, including neurons. Although Kir2.3 is known to be expressed abundantly in the forebrain, its precise localization has not been identified. Using an antibody specific to Kir2.3, we examined the subcellular localization of Kir2.3 in mouse brain. Kir2.3 immunoreactivity was detected in a granular pattern in restricted areas of the brain, including the olfactory bulb (OB). Immunoelectron microscopy of the OB revealed that Kir2.3 immunoreactivity was specifically clustered on the postsynaptic membrane of asymmetric synapses between granule cells and mitral/tufted cells. The immunoprecipitants for Kir2.3 obtained from brain contained PSD-95 and chapsyn-110, PDZ domain-containing anchoring proteins. In vitro binding assay further revealed that the COOH-terminal end of Kir2.3 is responsible for the association with these anchoring proteins. Therefore, the Kir channel may be involved in formation of the resting membrane potential of the spines and, thus, would affect the response of N-methyl-D-aspartic acid receptor channels at the excitatory postsynaptic membrane.
Inanobe
Atsushi
A
Department of Pharmacology II, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan.
Fujita
Akikazu
A
Ito
Minoru
M
Tomoike
Hitonobu
H
Inageda
Kiyoshi
K
Kurachi
Yoshihisa
Y
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000918:Antibody Specificity; D001921:Brain / Q000166:cytology / Q000378:metabolism; D002352:Carrier Proteins / Q000096:biosynthesis; D002460:Cell Line; D000074288:Discs Large Homolog 1 Protein; D000076122:Disks Large Homolog 4 Protein; D051528:Guanylate Kinases; D006801:Humans; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D008565:Membrane Proteins / Q000096:biosynthesis; D051379:Mice; D008807:Mice, Inbred BALB C; D016253:Microscopy, Immunoelectron; D009419:Nerve Tissue Proteins / Q000096:biosynthesis; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D009479:Neuropeptides / Q000096:biosynthesis; D009687:Nuclear Proteins; D009703:Nucleoside-Phosphate Kinase / Q000096:biosynthesis; D009830:Olfactory Bulb / Q000378:metabolism / Q000648:ultrastructure; D009928:Organ Specificity; D010750:Phosphoproteins / Q000096:biosynthesis; D015221:Potassium Channels / Q000096:biosynthesis*; D024661:Potassium Channels, Inwardly Rectifying; D051381:Rats; D017208:Rats, Wistar; D013569:Synapses / Q000378:metabolism* / Q000648:ultrastructure; D013570:Synaptic Membranes / Q000378:metabolism*; D014157:Transcription Factors; D062826:Zonula Occludens-1 Protein
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C513314:DLG1 protein, human; C116869:DLG3 protein, human; D000074288:Discs Large Homolog 1 Protein; D000076122:Disks Large Homolog 4 Protein; C000614189:Dlg1 protein, mouse; C501119:Dlg1 protein, rat; C101195:Dlg3 protein, rat; C501447:Dlg4 protein, mouse; C501449:Dlg4 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; C099489:KCNJ4 protein, human; C490969:Kcnj4 protein, mouse; C490968:Kcnj4 protein, rat; C114103:Magi2 protein, rat; D008565:Membrane Proteins; C501451:Mpp2 protein, rat; D009419:Nerve Tissue Proteins; D009479:Neuropeptides; D009687:Nuclear Proteins; D010750:Phosphoproteins; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; C569042:TJP1 protein, human; C569043:Tjp1 protein, mouse; C569044:Tjp1 protein, rat; D014157:Transcription Factors; D062826:Zonula Occludens-1 Protein; C033652:postsynaptic density proteins; D009703:Nucleoside-Phosphate Kinase; C501445:Dlg2 protein, mouse; C491075:Dlgh3 protein, mouse; D051528:Guanylate Kinases