1 Department of Pharmacology II, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871; 2 First Department of Internal Medicine, Yamagata University School of Medicine, Yamagata 990-9585; and 3 Hospital of National Cardiovascular Center, Suita, Osaka 565-8565, Japan
![]() |
ABSTRACT |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
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.
dendritic spine; ion channel localization; excitatory synaptic transmission
![]() |
INTRODUCTION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
INWARDLY RECTIFYING K+ (Kir) channels play pivotal roles in controlling the excitability of various cells, including neurons. The Kir channel subunit family contains >16 members, which can be classified into 4 major groups: background Kir channels (Kir2.0), G protein-gated Kir channels (Kir3.0), ATP-sensitive Kir channels (Kir6.0), and K+ transporters (Kir1.0, Kir4.0, and Kir7.0) (14, 15). The classical Kir2.0 channels are responsible for formation of the deep resting membrane potential near the K+ equilibrium potential in a variety of cells, such as cardiac and skeletal myocytes, glial cells, and some neurons. It was shown at the level of mRNA that Kir2.0 subunits are expressed differentially in various regions of the brain (11, 16, 36): Kir2.1 is expressed diffusely but weakly in the whole brain, Kir2.2 mainly in the cerebellum, Kir2.3 mainly in the forebrain, and Kir2.4 in motor neurons of the spinal cord. These observations indicate that members of the Kir2.0 subfamily may play different physiological roles in control of neuronal function. The subcellular localization of Kir2.0 channels in the brain, however, has not been extensively examined.
The mRNA of Kir2.3 is expressed predominantly in the forebrain (6, 21, 26, 35). In situ hybridization studies revealed that most Kir2.3 mRNA is found in neurons, rather than in glial cells (5, 11, 16). Furthermore, Kir2.3 binds to PSD-95, which scaffolds various functional proteins at the postsynaptic membrane of asymmetric synaptic junctions (5, 7, 23, 30). Although these results suggest that Kir2.3 is localized at the postsynaptic membrane of excitatory synapses, light microscopy indicated that neuronal Kir2.3 distributes diffusely in the nuclei and on the plasma membrane of pyramidal cells in the CA3 region of rat hippocampus (33). To resolve this paradox, we produced a polyclonal antibody specific to Kir2.3 and examined the localization of the channel protein in mouse brain at light- and electron-microscopic levels. The Kir2.3 immunoreactivity was detected in a granular pattern in limited regions of the forebrain, including the olfactory bulb (OB), neocortex, hippocampus, and caudate putamen. Immunoelectron-microscopic analysis in the OB revealed that Kir2.3 is specifically localized at the postsynaptic membrane of the dendritic spines of granule cells facing the secondary dendrites of mitral/tufted cells. The distribution of Kir2.3 at sites of excitatory postsynaptic specialization suggests that this channel participates in the formation of the membrane potential of the spines.
![]() |
MATERIALS AND METHODS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Antibodies. Animals were treated in accordance with the guidelines for the use of laboratory animals of Osaka University Medical School. A rabbit polyclonal antibody (mI3C3) was generated against a synthetic polypeptide, LGLEAGSKEEAGIIRMLEFGSHL, corresponding to amino acids 400-422 of mouse Kir2.3 (21). Cysteine was added at the NH2 terminus of the peptide to couple to ovalbumin for the preparation of immunogen and to SulfoLink coupling gel (Pierce, Rockford, IL) for purification of antigenic peptide-specific IgG. Affinity purification of mI3C3 antibody was carried out with sequential column chromatography through protein A-Sepharose (Amersham Pharmacia Biotech, Uppsala, Sweden) and antigenic peptide-coupled resins from antiserum. To detect PDZ domain-containing proteins, we used monoclonal anti-PSD-95 and anti-dlg/SAP97 antibodies (clones 16 and 12, respectively; Transduction Laboratories, Lexington, KY), rabbit anti-SAP102 and anti-S-SCAM (kindly provided by Dr. Y. Takai) and anti-chapsyn-110 antibodies (APZ-002, Alomone Laboratory, Jerusalem, Israel), and goat anti-ZO-1 antibody (N-19; Santa Cruz Biotechnology, Santa Cruz, CA).
Immunoblotting, immunocytochemistry, and immunohistochemistry. Mouse Kir2.3 (21) and rat PSD-95 (kindly provided by Dr. Y. Takai) were subcloned into expression vector pcDNA3 (InVitrogen, San Diego, CA). The constructs and rat chapsyn-110 in GW1 (generous gift from Dr. M. Sheng) were transiently expressed in human embryonic kidney (HEK) 293T cells with the LipofectAMINE PLUS reagent (InVitrogen). The cell lysate and membrane fraction of various tissues from Balb/c mice were prepared as described previously (13). The proteins were subjected to SDS-PAGE and transferred to polyvinylidine difluoride membranes. Kir2.3 immunoreactivity was developed with the SuperSignal chemiluminescence kit (Pierce).
Cells expressing Kir2.3 were also fixed with 4% (wt/vol) paraformaldehyde (PFA) in 0.1 M sodium phosphate buffer (PB), pH 7.4, at 4°C overnight. After the cells were washed with phosphate-buffered saline (PBS), they were incubated with mI3C3 antibody and then with FITC-conjugated anti-rabbit antibody and propidium iodide for staining nuclei, as described previously (13). Fluorescence was measured using laser scanning confocal microscopy (system LSM510, Carl Zeiss, Oberkochen, Germany). Immunohistochemistry was carried out as described previously (13). Briefly, Balb/c mice were deeply anesthetized with pentobarbital sodium (60 mg/kg ip) and perfused transcardially with 4% PFA in 0.1 M PB (pH 7.4). The brains were dissected, postfixed in the same solution at 4°C for 12 h, and then dehydrated in 30% (wt/wt) sucrose and 0.05% (wt/vol) NaN3 in PBS at 4°C. The parasagittal sections (20 µm thick) were prepared with a cryostat and stored in PBS supplemented with 0.1% (wt/vol) Triton X-100 and 0.05% NaN3 at 4°C. Cryosections were immunostained by the free-floating method with incubation of mI3C3 (0.5 µg/ml) at 4°C for 48 h and then biotinylated goat anti-rabbit IgG (Vectastain ABC kit, Vector Laboratories, Burlingame, CA). The immunoreactivity was developed with H2O2, diaminobenzidine (DAB), and nickel ammonium. The same antibody preincubated with 100-fold antigenic peptide was also used for control staining.Immunoelectron microscopy. Postembedding immunogold electron-microscopic examination was performed with mouse brain fixed by the "pH-shift" protocol (10, 19). Ultrathin sections were cut from small blocks of OB with a Reichert ultramicrotome and mounted on nickel grids. Immunoreactivity of Kir2.3 was developed with mI3C3 (1 µg/ml) and then with 10-nm colloidal gold particle-conjugated F(ab)2 fragment (GFAR10, British BioCell International, Cardiff, UK). Electron-microscopic examination for the DAB-developed Kir2.3 immunoreactivity was carried out with mouse brain fixed by periodate-lysine-PFA (13). Sections were incubated with mI3C3 antibody and then with biotinylated goat anti-rabbit IgG (Vectastain ABC kit). After color development with DAB, nickel ammonium, and platinous potassium chloride, the sections were postfixed in reduced osmium, infiltrated with epoxy resin, and then sectioned with an ultramicrotome. Finally, the sections obtained with both procedures were counterstained with uranyl acetate and Reynolds' lead citrate and examined in an electron microscope (model 7100, Hitachi, Tokyo, Japan).
Immunoprecipitation.
Three forebrains dissected from Wistar rats were homogenized with
Physcotron (NITI-ON Medical Physical Instrument, Tokyo, Japan) and then
with a tight-fitting glass-Teflon homogenizer in 30 ml of 50 mM
Tris · HCl (pH 7.5), 1 mM EDTA, and protease inhibitor cocktail
(1 mM phenylmethylsulfonyl fluoride, 0.2 mg/ml benzamidine · HCl, and 5 µg/ml each of pepstatin, leupeptin,
and chymostatin). After centrifugation at 100,000 g for 30 min, the sedimented membrane fraction was suspended with 30 ml of 50 mM Tris · HCl (pH 8.6), 1 mM Na-EDTA, 1% (wt/vol) deoxycholate
(DOC), and protease inhibitor cocktail, homogenized with a glass-Teflon homogenizer, and then centrifuged at 100,000 g for 30 min.
The soluble fraction was supplemented with Triton X-100 to give a final
concentration of 0.3% and dialyzed against 3 liters of 20 mM
Tris · HCl (pH 7.5), 150 mM NaCl, and 0.1% Triton X-100 at 4°C overnight. After the addition of protease inhibitor cocktail, the
DOC extract was clarified by centrifugation and stored at 80°C.
Immunoprecipitation was carried out as described previously (13). Briefly, Kir2.3 in 1 ml of the DOC extract (30 mg of
protein) was recovered with 2 µg of mI3C3 and protein G-Sepharose
beads (Amersham Pharmacia Biotech). Rabbit nonimmune IgG or mI3C3
antibody preincubated with a 100-fold amount of its antigenic peptide
was used for negative control. Protein retained on beads was eluted with 20 µl of loading buffer, resolved by SDS-PAGE, and detected by
immunoblotting with a series of antibodies.
Affinity chromatography.
Amino acids 298-445 and 298-441 of mouse Kir2.3, amino acids
1434-1482 of rat N-methyl-D-aspartic acid
(NMDA) receptor 2B (NR2B), and amino acids 605-655 of rat
voltage-dependent K+ channel Kv1.4 were amplified by
polymerase chain reaction to tag BamHI and XhoI
sites at 5' or 3' ends, respectively, and subcloned into pGEX-4T-1
(Amersham Pharmacia Biotech). The sequence of constructs was verified
by an ABI dye terminator cycle sequencing kit with the ABI PRISM 310 Genetic Analyzer (Applied Biosystems, Foster city, CA). Glutathione
(GST)-fusion proteins were expressed in Escherichia
coli strain BL21 (DE3) pLysS (Promega, Madison, WI) and
purified on GST-Sepharose (Amersham Pharmacia Biotech). Purified proteins were dialyzed against PBS and stored at 80°C. Each
GST-fusion protein (10 µg) bound on GST-Sepharose was mixed with the
DOC extract (10 mg of protein) from rat brain or the cell extract (10 µg of protein) expressing PSD-95 or chapsyn-110 and rotated at 4°C
for 2 h. The resin was washed once with 1 ml of 20 mM
HEPES · NaOH (pH 7.4), 1 mM Na-EDTA, 1 mM dithiothreitol, and
protease inhibitor cocktail (base solution) supplemented with 1%
Triton X-100 and 0.15 M NaCl, twice with 1 ml of base solution with 1% Triton X-100 and 0.5 M NaCl, and twice with 1 ml of base solution with
0.15 M NaCl. Bound proteins were analyzed with the immunoblotting technique described above.
Nomenclature. Anatomic examinations were carried out with the main OB. Therefore, the term OB represents the main OB. Nevertheless, we could not detect any significant difference in Kir2.3 localization between the main OB and accessory OB at the light-microscopic level. The term mitral cell represents mitral and tufted cells, because we could not distinguish between their dendrites under our conditions.
![]() |
RESULTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Characterization of anti-Kir2.3 antibody.
To examine the localization of Kir2.3 channel protein expressed in
neural tissues, we developed a polyclonal antibody against a synthetic
peptide corresponding to the COOH terminus of mouse Kir2.3
(21). After purification of the IgG fraction through protein A- and antigenic peptide-coupled resins from antiserum, we
characterized the IgG (mI3C3) by immunoblotting and immunocytochemical analyses (Fig. 1). As shown in Fig.
1A, the antibody developed several bands at ~55 kDa in the
lysate from HEK 293T cells expressing Kir2.3 (lane 1). These
bands were not detected in the control cell lysate (lane 2).
The antibody preincubated with excess antigenic peptide failed to
detect any bands (lane 3). The duplicated major protein
bands at ~55 kDa were also detected in the membrane fraction obtained
from mouse forebrain (lane 4), but not from cerebellum (lane 5). Kir2.3 immunoreactivity was examined in other
tissues by overexposing the film until the duplicated bands of Kir2.3 in the forebrain were indistinguishable (Fig. 1B). There
were no significant signals in the tissues examined other than the forebrain. The distribution of Kir2.3 immunoreactivity agreed with that
of Kir2.3 mRNA shown by Northern blotting (6, 21, 26, 35).
The specificity of the mI3C3 antibody was tested with
immunocytochemistry (Fig. 1C). Kir2.3, transiently expressed in HEK 293T cells, was detected with this antibody (Fig.
1Ca), but not with the antibody preincubated with antigenic
peptide (Fig. 1Cb). The signal was not detected in the cells
that were not transfected with Kir2.3 cDNA (Fig. 1Cc). The
mI3C3 antibody used in this study, therefore, specifically recognizes
mouse Kir2.3.
|
Immunolocalization of Kir2.3 in mouse brain.
Using the mI3C3 antibody, we first examined the distribution of Kir2.3
in sagittal slices of mouse brain at the level of light microscopy
(Fig. 2). Kir2.3 immunoreactivity was
preferentially detected in several areas of the forebrain (Fig.
2A), which is consistent with the result of immunoblotting
analysis (Fig. 1, A and B). No significant signal
was developed with the antibody preincubated with the antigenic peptide
(Fig. 2B). The Kir2.3 signal was found strongly in the OB,
olfactory tubercle, neocortex, caudate putamen, and hippocampus and
weakly in the inferior colliculus. In these areas, the immunoreactivity
showed a granular pattern (Fig. 2, D-F). The
distribution of Kir2.3 immunoreactivity was consistent with that of its
mRNA shown by in situ hybridization studies (5, 11, 16,
17).
|
Electron-microscopic study of Kir2.3 in mouse OB.
The dendritic spines of granule cells contact with the secondary
dendrites of mitral cells in the EPL, and most such synapses exist as
pairs of reciprocal contacts (Fig. 2G) (32). In
the electron-microscopic images of the EPL (Fig.
3), the reciprocal synapses could be
easily identified as the contacts between the relatively smooth
dendrites of mitral cells, which contain round vesicles, and the
dendritic spines of granule cells, which contain flattened vesicles.
The preembedding method was applied first to detect immunoreactivity of
Kir2.3 (Fig. 3, A and B). Dark-colored DAB-immunoreactive Kir2.3 was detected in granule cell spines (Fig.
3A). Substantial immunoreactivity was detected in the
vicinity of the plasma membrane of granule cells facing mitral cell
dendrites (Fig. 3B). Although we searched for Kir2.3
immunoreactivity in the superficial area of the OB, no signal could be
found at the synaptic contacts between periglomerular cells and mitral
cells or at synapses between nerve termini of olfactory epithelium and primary dendrites of mitral cells (data not shown). Kir2.3
immunoreactivity was specifically localized on the plasma membrane of
the dendritic spines of granule cells in contact with the dendrites of
mitral cells in the EPL of the OB.
|
Molecular basis for specific localization of Kir2.3 on excitatory
postsynaptic membrane.
At the postsynaptic membrane of excitatory synapses, PDZ
(PSD-95/dlg/ZO-1) domain-containing proteins scaffold many functional proteins, including NMDA receptors and voltage-dependent K+
channels (7, 30). Kir2.3 possesses a COOH-terminal
sequence corresponding to a class I PDZ domain-binding motif, i.e.,
Glu-Ser-Ala-Ile, and has been reported to interact with the anchoring
protein PSD-95 (5, 23). Because Kir2.3 was specifically
distributed at the excitatory postsynaptic membrane of dendritic spines
of granule cells in the OB, we looked for possible PDZ
domain-containing anchoring proteins that could associate with it (Fig.
4A). With the use of a series
of antibodies, PSD-95 and chapsyn-110 were identified in the
immunoprecipitants with mI3C3 obtained from the DOC extract of rat
brain (lane 3). Neither nonimmune IgG nor mI3C3 preincubated
with excess antigenic peptide immunoprecipitated the protein complex
containing these PDZ domain-containing proteins (lanes 2 and
4, respectively). Neither SAP102, SAP97, S-SCAM, nor ZO-1
was detected in the immunoprecipitants. These results suggest that
PSD-95 and/or chapsyn-110 forms protein complexes with Kir2.3 in the
brain.
|
![]() |
DISCUSSION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
This study shows that Kir2.3 protein is specifically localized on
the excitatory postsynaptic membrane of dendritic spines of granule
cells in the OB. At the reciprocal synapses in the EPL of the OB, the
NMDA receptor NR1 and
-amino-3-hydroxyl-5-methylisoxazole-4-propionic acid receptors GluR2
and GluR3 are present at the asymmetric postsynaptic membrane on
granule cell spines (28). The distribution of these channel proteins within the postsynaptic membrane is essentially the
same as in other excitatory synapses (2, 8, 19);
therefore, the molecular organization at the postsynaptic density of
reciprocal asymmetric synapses in the OB may be similar to that of
other excitatory synapses. At the light-microscopic level, Kir2.3
immunoreactivity exhibited a granular pattern not only in the OB but
also in other regions in the forebrain (Fig. 2). Thus Kir2.3 may play
an important functional role in excitatory synaptic transmission in the forebrain.
The COOH-terminal end of Kir2.3 possesses a PDZ domain-binding motif, which is considered to account for the interaction with PSD-95 (5, 23). Cohen et al. (5) biochemically isolated the protein complex of PSD-95 and Kir2.3, not only from rat forebrain but also from the OB. In addition to PSD-95, we showed that chapsyn-110 forms a protein complex with Kir2.3 through the interaction with its COOH-terminal end (Fig. 4). In rat forebrain, the expression pattern of chapsyn-110 mRNA largely overlaps with that of PSD-95 mRNA (3). Because chapsyn-110 is closely related to PSD-95 (85% similarity) and has a potency comparable to that of PSD-95 in NMDA receptor-clustering activity (3, 18), PSD-95 and chapsyn-110 may be responsible for the specific localization of Kir2.3 at the postsynaptic membrane of excitatory synapses.
Dendritic spines are neuronal compartments that protrude from the dendrite, and it is postulated that they behave separately from the dendrite biochemically and electrically (for review see Ref. 31). The spine also functions as the site of excitatory synaptic input (31). Therefore, the situation of the Kir2.3 channel on the excitatory postsynaptic membrane may contribute to form a resting membrane potential for the spines that is more negative than that of the dendrites. Most glutaminergic synaptic input terminates on the spines, and ionotropic and metabotropic glutamate receptors are found at the excitatory postsynaptic membrane of the spines (31). Because the behavior of NMDA receptor channels is voltage dependent due to block by Mg2+ (20, 25), the Kir2.3 channel might be a factor contributing to the response of NMDA receptor channels at the postsynaptic membrane.
Although specific modulation of Kir2.3 channels at excitatory postsynaptic membranes has not been reported, Nehring et al. (23) showed that association of PSD-95 causes reduction of the single-channel conductance of Kir2.3, although the physiological role is not clear. Various background Kir channel currents have been shown to be suppressed by the activation of Gq-coupled neurotransmitter receptors. They include group I metabotropic glutamate receptors in various neurons, including granule cells in the OB (1, 34), substance P receptors in nucleus basalis neurons (22), 5-hydroxytryptamine receptors in nucleus accumben neurons (24), and muscarine receptors in locus ceruleus neurons (29). Inhibition may be due to reduction of phosphatidylinositol 4,5-bisphosphate (PIP2) content in the cell membrane through the activation of phospholipase C. PIP2 is an essential lipid for the maintenance of the activity of Kir channels (12). Therefore, Kir2.3 channel activity modulated by Gq-coupled receptors may affect synaptic transmission at some excitatory synapses. In addition to PIP2, cytoplasmic ATP (6), inter- and extracellular pH (27, 37), phosphorylation by protein kinase C (9, 38), and intracellular Mg2+ (4) have been found to modulate Kir2.3 activity. Thus Kir2.3 is potentially an important target of various signaling systems in the spines. Further studies are needed to clarify the physiological role of Kir2.3 channels at excitatory postsynaptic membranes.
![]() |
ACKNOWLEDGEMENTS |
---|
The authors thank Dr. I. Findlay (Tours University, Tours, France) for critical reading of the manuscript, K. Iwai for technical assistance, and K. Tsuji for secretarial work.
![]() |
FOOTNOTES |
---|
This work was supported by Ministry of Education, Culture, Sports, and Science of Japan Grant-in-Aid for Scientific Research on Priority Areas 12144207 to Y. Kurachi and Grant-in-Aid for Encouragement of Young Scientists 13780615 to A. Inanobe.
Address for reprint requests and other correspondence: Y. Kurachi, Dept. of Pharmacology II A7, Graduate School of Medicine, Osaka University, Yamada-oka 2-2, Suita, Osaka 565-0871, Japan (E-mail: ykurachi{at}pharma2.med.osaka-u.ac.jp).
The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
10.1152/ajpcell.00615.2001
Received 26 December 2001; accepted in final form 29 January 2002.
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
1.
Anwyl, R.
Metabotropic glutamate receptors: electrophysiological properties and role in plasticity.
Brain Res Rev
29:
83-120,
1999[ISI][Medline].
2.
Bernard, V,
and
Bolam JP.
Subcellular and subsynaptic distribution of the NR1 subunit of the NMDA receptor in the neostriatum and globus pallidus of the rat: co-localization at synapses with the GluR2/3 subunit of the AMPA receptor.
Eur J Neurosci
10:
3721-3736,
1998[ISI][Medline].
3.
Brenman, JE,
Christopherson KS,
Craven SE,
McGee AW,
and
Bredt DS.
Cloning and characterization of postsynaptic density 93, a nitric oxide synthase interacting protein.
J Neurosci
16:
7407-7415,
1996
4.
Chuang, H,
Jan YN,
and
Jan LY.
Regulation of IRK3 inward rectifier K+ channel by m1 acetylcholine receptor and intracellular magnesium.
Cell
89:
1121-1132,
1997[ISI][Medline].
5.
Cohen, NA,
Brenman JE,
Snyder SH,
and
Bredt DS.
Binding of the inward rectifier K+ channel Kir2.3 to PSD-95 is regulated by protein kinase A phosphorylation.
Neuron
17:
759-767,
1996[ISI][Medline].
6.
Collins, A,
German MS,
Jan YN,
Jan LY,
and
Zhao B.
A strongly inwardly rectifying K+ channel that is sensitive to ATP.
J Neurosci
16:
1-9,
1996[Abstract].
7.
Craven, SE,
and
Bredt DS.
PDZ proteins organize synaptic signaling pathways.
Cell
93:
495-498,
1998[ISI][Medline].
8.
He, Y,
Janssen WG,
and
Morrison JH.
Synaptic coexistence of AMPA and NMDA receptors in the rat hippocampus: a postembedding immunogold study.
J Neurosci Res
54:
444-449,
1998[ISI][Medline].
9.
Henry, P,
Pearson WL,
and
Nichols CG.
Protein kinase C inhibition of cloned inward rectifier (HRK1/Kir2.3) K+ channels expressed in Xenopus oocytes.
J Physiol
495:
681-688,
1996[Abstract].
10.
Hibino, H,
Horio Y,
Fujita A,
Inanobe A,
Doi K,
Kubo T,
and
Kurachi
Expression of an inwardly rectifying K+ channel, Kir4.1, in satellite cells of rat cochlear ganglia.
Am J Physiol Cell Physiol
277:
C638-C644,
1999
11.
Horio, Y,
Morishige K,
Takahashi N,
and
Kurachi Y.
Differential distribution of classical inwardly rectifying potassium channel mRNAs in the brain: comparison of IRK2 with IRK1 and IRK3.
FEBS Lett
379:
239-243,
1996[ISI][Medline].
12.
Huang, CL,
Feng S,
and
Hilgemann DW.
Direct activation of inward rectifier potassium channels by PIP2 and its stabilization by G.
Nature
391:
803-806,
1998[ISI][Medline].
13.
Inanobe, A,
Yoshimoto Y,
Horio Y,
Morishige K,
Hibino H,
Matsumoto S,
Tokunaga Y,
Maeda T,
Hata Y,
Takai Y,
and
Kurachi Y.
Characterization of G-protein-gated K+ channels composed of Kir3.2 subunits in dopaminergic neurons of the substantia nigra.
J Neurosci
19:
1006-1017,
1999
14.
Isomoto, S,
Kondo C,
and
Kurachi Y.
Inwardly rectifying potassium channels: their molecular heterogeneity and function.
Jpn J Physiol
47:
11-39,
1997[ISI][Medline].
15.
Jan, LY,
and
Jan YN.
Receptor-regulated ion channels.
Curr Opin Cell Biol
9:
155-160,
1997[ISI][Medline].
16.
Karschin, C,
Dissmann E,
Stühmer W,
and
Karschin A.
IRK(1-3) and GIRK(1-4) inwardly rectifying K+ channel mRNAs are differentially expressed in the adult rat brain.
J Neurosci
16:
3559-3570,
1996
17.
Karschin, C,
and
Karschin A.
Ontogeny of gene expression of Kir channel subunits in the rat.
Mol Cell Neurosci
10:
131-148,
1997[ISI].
18.
Kim, E,
Cho KO,
Rothschild A,
and
Sheng M.
Heteromultimerization and NMDA receptor-clustering activity of chapsyn-110, a member of the PSD-95 family of proteins.
Neuron
17:
103-113,
1996[ISI][Medline].
19.
Matsubra, A,
Laake JH,
Davanger S,
Usami S,
and
Ottersen OP.
Organization of AMPA receptor subunits at a glutamate synapse: a quantitative immunogold analysis of hair cell synapses in the rat organ of Corti.
J Neurosci
16:
4457-4467,
1996
20.
Mayer, LM,
Westbrook GL,
and
Guthrie PB.
Voltage-dependent block by Mg2+ of NMDA responses in spinal cord neurons.
Nature
309:
261-263,
1984[ISI][Medline].
21.
Morishige, K,
Takahashi N,
Jahangir A,
Yamada M,
Koyama H,
Zanelli JS,
and
Kurachi Y.
Molecular cloning and functional expression of a novel brain-specific inward rectifier potassium channel.
FEBS Lett
346:
251-256,
1994[ISI][Medline].
22.
Nakajima, Y,
Nakajima S,
and
Inoue M.
Pertussis toxin-insensitive G protein mediates substance P-induced inhibition of potassium channels in brain neurons.
Proc Natl Acad Sci USA
85:
3643-3647,
1988[Abstract].
23.
Nehring, RB,
Wischmeyer E,
Döring F,
Veh RW,
Sheng M,
and
Karschin A.
Neuronal inwardly rectifying K+ channels differentially couple to PDZ proteins of the PSD-95/SAP90 family.
J Neurosci
20:
156-162,
2000
24.
North, RA,
and
Uchimura N.
5-Hydroxytryptamine acts at 5-HT2 receptors to decrease potassium conductance in rat nucleus accumbens neurones.
J Physiol
417:
1-12,
1989[Abstract].
25.
Nowak, L,
Bregestovski P,
Ascher P,
Herbet A,
and
Prochiantz A.
Magnesium gates glutamate-activated channels in mouse central neurones.
Nature
307:
462-465,
1984[ISI][Medline].
26.
Périer, F,
Radeke CM,
and
Vandenberg CA.
Primary structure and characterization of a small-conductance inwardly rectifying potassium channel from human hippocampus.
Proc Natl Acad Sci USA
91:
6240-6244,
1994[Abstract].
27.
Qu, Z,
Zhu G,
Yang Z,
Cui N,
Li Y,
Chanchevalap S,
Sulaiman S,
Hynie H,
and
Jiang C.
Identification of a critical motif responsible for gating of Kir2.3 channel by intracellular protons.
J Biol Chem
274:
13783-13789,
1999
28.
Sassoé-Pognetto, M,
and
Ottersen OP.
Organization of ionotropic glutamate receptors at dendrodendritic synapses in the rat olfactory bulb.
J Neurosci
20:
2192-2201,
2000
29.
Shen, KZ,
and
North RA.
Muscarine increases cation conductance and decreases potassium conductance in rat locus coeruleus neurones.
J Physiol
455:
471-485,
1992[Abstract].
30.
Sheng, M.
PDZs and receptor/channel clustering: rounding up the latest suspects.
Neuron
17:
575-578,
1996[ISI][Medline].
31.
Shepherd, GM.
The dendritic spine: a multifunctional integrative unit.
J Neurophysiol
75:
2197-2210,
1996
32.
Shepherd, GM,
and
Greer CA.
Olfactory bulb.
In: The Synaptic Organization of the Brain (4th ed.). New York: Oxford University Press, 1998, p. 159-203.
33.
Stonehouse, AH,
Pringle JH,
Norman RI,
Stanfield PR,
Conley EC,
and
Brammar WJ.
Characterisation of Kir2.0 proteins in the rat cerebellum and hippocampus by polyclonal antibodies.
Histochem Cell Biol
112:
457-465,
1999[ISI][Medline].
34.
Takeshita, Y,
Harata N,
and
Akaike N.
Suppression of K+ conductance by metabotropic glutamate receptor in acutely dissociated large cholinergic neurons of rat caudate putamen.
J Neurophysiol
76:
1545-1558,
1996
35.
Tang, W,
and
Yang XC.
Cloning a novel human brain inward rectifier potassium channel and its functional expression in Xenopus oocytes.
FEBS Lett
348:
239-243,
1994[ISI][Medline].
36.
Topert, C,
Doring F,
Wischmeyer E,
Karschin C,
Brockhaus J,
Derst C,
and
Karschin A.
Kir2.4: a novel K+ inward rectifier channel associated with motoneurons of cranial nerve nuclei.
J Neurosci
18:
4096-4105,
1998
37.
Zhu, G,
Chanchevalap S,
Cui N,
and
Jiang C.
Effects of intra- and extracellular acidifications on single channel Kir2.3 currents.
J Physiol
516:
699-710,
1999
38.
Zhu, G,
Qu Z,
Cui N,
and
Jiang C.
Suppression of Kir2.3 activity by protein kinase C phosphorylation of the channel protein at threonine 53.
J Biol Chem
274:
11643-11646,
1999