電位開口型K+チャネル、電位開口型カリウムチャネル、電位依存性K+チャネル

関: voltage-dependent K+ channel、voltage-dependent potassium channel、voltage-gated potassium channel

WordNet

direct the flow of; "channel information towards a broad audience" (同)canalize, canalise
a television station and its programs; "a satellite TV channel"; "surfing through the channels"; "they offer more than one hundred channels" (同)television channel, TV channel
a passage for water (or other fluids) to flow through; "the fields were crossed with irrigation channels"; "gutters carried off the rainwater into a series of channels under the street"
(often plural) a means of communication or access; "it must go through official channels"; "lines of communication were set up between the two firms" (同)communication channel, line
a path over which electrical signals can pass; "a channel is typically what you rent from a telephone company" (同)transmission channel
a deep and relatively narrow body of water (as in a river or a harbor or a strait linking two larger bodies) that allows the best passage for vessels; "the ship went aground in the channel"
supply with a gate; "The house was gated"
restrict (school boys'
total admission receipts at a sports event
a computer circuit with several inputs but only one output that can be activated by particular combinations of inputs (同)logic gate
a movable barrier in a fence or wall
passageway (as in an air terminal) where passengers can embark or disembark
control with a valve or other device that functions like a gate
United States guitar player and singer of the blues (born in 1925) (同)B. B. King, Riley B King
United States woman tennis player (born in 1943) (同)Billie Jean King, Billie Jean Moffitt King
United States charismatic civil rights leader and Baptist minister who campaigned against the segregation of Blacks (1929-1968) (同)Martin Luther King, Martin Luther King Jr.
street names for ketamine (同)jet, super acid, special K, honey oil, green, cat valium, super C
the 11th letter of the Roman alphabet (同)k
the rate at which energy is drawn from a source that produces a flow of electricity in a circuit; expressed in volts (同)electromotive_force, emf

PrepTutorEJDIC

〈C〉『水路』(川・湾・運河の船の通行ができる深い部分) / 〈U〉河床・川底 / 〈C〉『海峡』 / 〈C〉みぞ(groove),(道路の)水渠(すいきょ) / 《複数形で》(運搬・伝達の)正式の経路(手続き);(一般に)経路 / 〈C〉(テレビ・ラジオの)チャンネル / …‘に'水路を開く / …‘に'みぞを堀る / …'を'伝える,流す
(…への)『門』,通用門《+『to』(『of』)+『名』》;(門の)とびら / (ダム・運河などの)水門 / (競技場・劇場などの)[有料]入場者数 / (またgate money)総入場料
Kelvin / Kindergarten / (チェスの)King / kalium(ラテン語)(=potassium)の化学記号
電圧,電圧量,ボルト数

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/04/24 15:11:24」(JST)

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Slow voltage-gated potassium channel (Potassium channel, voltage-dependent, beta subunit, KCNE)

Identifiers

Symbol

ISK_Channel

Pfam

PF02060

InterPro

IPR000369

TCDB

8.A.10

Available protein structures:
Pfam	structures
PDB	RCSB PDB; PDBe
PDBsum	structure summary

KCNQ voltage-gated potassium channe

Identifiers

Symbol

KCNQ_channel

Pfam

PF03520

InterPro

IPR013821

Available protein structures:
Pfam	structures
PDB	RCSB PDB; PDBe
PDBsum	structure summary

Kv2 voltage-gated K+ channel

Identifiers

Symbol

Kv2channel

Pfam

PF03521

InterPro

IPR003973

Available protein structures:
Pfam	structures
PDB	RCSB PDB; PDBe
PDBsum	structure summary

Voltage-gated potassium channels are transmembrane channels specific for potassium and sensitive to voltage changes in the cell's membrane potential. During action potentials, they play a crucial role in returning the depolarized cell to a resting state.

1 Classification
- 1.1 Alpha subunits
  - 1.1.1 Delayed rectifier
  - 1.1.2 A-type potassium channel
  - 1.1.3 Outward-rectifying
  - 1.1.4 Inward-rectifying
  - 1.1.5 Slowly activating
  - 1.1.6 Modifier/silencer
- 1.2 Beta subunits
2 Animal research
3 Structure
4 Selectivity
5 Open and closed conformations
6 See also
7 References
8 External links

Classification

Alpha subunits

Alpha subunits form the actual conductance pore. Based on sequence homology of the hydrophobic transmembrane cores, the alpha subunits of voltage-gated potassium channels are grouped into 12 classes. These are labeled K_vα1-12.^[1] The following is a list of the 40 known human voltage-gated potassium channel alpha subunits grouped first according to function and then subgrouped according to the K_v sequence homology classification scheme:

Delayed rectifier

slowly inactivating or non-inactivating

K_vα1.x - Shaker-related: K_v1.1 (KCNA1), K_v1.2 (KCNA2), K_v1.3 (KCNA3), K_v1.5 (KCNA5), K_v1.6 (KCNA6), K_v1.7 (KCNA7), K_v1.8 (KCNA10)
K_vα2.x - Shab-related: K_v2.1 (KCNB1), K_v2.2 (KCNB2)
K_vα3.x - Shaw-related: K_v3.1 (KCNC1), K_v3.2 (KCNC2)
K_vα7.x: K_v7.1 (KCNQ1) - KvLQT1, K_v7.2 (KCNQ2), K_v7.3 (KCNQ3), K_v7.4 (KCNQ4), K_v7.5 (KCNQ5)
K_vα10.x: K_v10.1 (KCNH1)

A-type potassium channel

rapidly inactivating

K_vα1.x - Shaker-related: K_v1.4 (KCNA4)
K_vα3.x - Shaw-related: K_v3.3 (KCNC3), K_v3.4 (KCNC4)
K_vα4.x - Shal-related: K_v4.1 (KCND1), K_v4.2 (KCND2), K_v4.3 (KCND3)

Outward-rectifying

K_vα10.x: K_v10.2 (KCNH5)

Inward-rectifying

Passes current more easily into the inwards direction (Into the cell).

K_vα11.x - ether-a-go-go potassium channels: K_v11.1 (KCNH2) - hERG, K_v11.2 (KCNH6), K_v11.3 (KCNH7)

Slowly activating

K_vα12.x: K_v12.1 (KCNH8), K_v12.2 (KCNH3), K_v12.3 (KCNH4)

Modifier/silencer

Unable to form functional channels as homotetramers but instead heterotetramerize with K_vα2 family members to form conductive channels.

K_vα5.x: K_v5.1 (KCNF1)
K_vα6.x: K_v6.1 (KCNG1), K_v6.2 (KCNG2), K_v6.3 (KCNG3), K_v6.4 (KCNG4)
K_vα8.x: K_v8.1 (KCNV1), K_v8.2 (KCNV2)
K_vα9.x: K_v9.1 (KCNS1), K_v9.2 (KCNS2), K_v9.3 (KCNS3)

Beta subunits

Beta subunits are auxiliary proteins that associate with alpha subunits, sometimes in a α₄β₄ stoichiometry.^[2] These subunits do not conduct current on their own but rather modulate the activity of K_v channels.^[3]

K_vβ1 (KCNAB1)
K_vβ2 (KCNAB2)
K_vβ3 (KCNAB3)
minK^[4] (KCNE1)
MiRP1^[5] (KCNE2)
MiRP2 (KCNE3)
MiRP3 (KCNE4)
KCNE1-like (KCNE1L)
KCNIP1 (KCNIP1)
KCNIP2 (KCNIP2)
KCNIP3 (KCNIP3)
KCNIP4 (KCNIP4)

Proteins minK and MiRP1 are putative hERG beta subunits.^[6]

Animal research

The voltage-gated K⁺ channels that provide the outward currents of action potentials have similarities to bacterial K⁺ channels.

These channels have been studied by X-ray diffraction, allowing determination of structural features at atomic resolution.

The function of these channels is explored by electrophysiological studies.

Genetic approaches include screening for behavioral changes in animals with mutations in K⁺ channel genes. Such genetic methods allowed the genetic identification of the "Shaker" K⁺ channel gene in Drosophila before ion channel gene sequences were well known.

Study of the altered properties of voltage-gated K⁺ channel proteins produced by mutated genes has helped reveal the functional roles of K⁺ channel protein domains and even individual amino acids within their structures.

Structure

Typically, vertebrate voltage-gated K⁺ channels are tetramers of four identical subunits arranged as a ring, each contributing to the wall of the trans-membrane K⁺ pore. Each subunit is composed of six membrane spanning hydrophobic α-helical sequences. The high resolution crystallographic structure of the rat K_vα1.2/β2 channel has recently been solved (Protein Databank Accession Number 2A79),^[7] and then refined in a lipid membrane-like environment (PDB 2r9r).

Selectivity

Main article: Potassium_channel#Selectivity_filter

Voltage-gated K⁺ channels are selective for K⁺ over other cations such as Na⁺. There is a selectivity filter at the narrowest part of the transmembrane pore.

Channel mutation studies have revealed the parts of the subunits that are essential for ion selectivity. They include the amino acid sequence (Thr-Val-Gly-Tyr-Gly) or (Thr-Val-Gly-Phe-Gly) typical to the selectivity filter of voltage-gated K⁺ channels. As K⁺ passes through the pore, interactions between potassium ions and water molecules are prevented and the K⁺ interacts with specific atomic components of the Thr-Val-Gly-X-Gly sequences from the four channel subunits[1].

It seems illogical at first that a channel should be able to allow potassium ions but not the smaller sodium ions through. However in an aqueous environment, potassium and sodium cations are solvated by water molecules. When moving through the selectivity filter of the potassium channel, the water-K⁺ interactions are replaced by interactions between K⁺ and carbonyl groups of the channel protein. The diameter of the selectivity filter is ideal for the potassium cation, but too big for the smaller sodium cation. Hence the potassium cations are well "solvated" by the protein carbonyl groups, but these same carbonyl groups are too far apart to adequately solvate the sodium cation. Hence, the passage of potassium cations through this selectivity filter is strongly favored over sodium cations.

Open and closed conformations

Attempts continue to relate the structure of the mammalian voltage-gated K⁺ channel to its ability to respond to the voltage that exists across the membrane.^[8] Specific domains of the channel subunits have been identified that are important for voltage-sensing and converting between the open conformation of the channel and closed conformations. There are at least two closed conformations; in one, the channel can open if the membrane potential becomes positive inside. Voltage-gated K⁺ channels inactivate after opening, entering a distinctive, second closed conformation. In the inactivated conformation, the channel cannot open, even if the transmembrane voltage is favorable. The amino terminal domain of the K⁺ channel or an auxiliary protein can mediate "N-type" inactivation. The former has been described as a "ball and chain" model, where the N-terminus of the protein forms a ball that is tethered to the rest of the protein through a loop (the chain). The tethered ball is transiently sucked into the inner porehole, preventing ion movement through the channel.^[9]^[10]

References

^ Gutman GA, Chandy KG, Grissmer S, Lazdunski M, McKinnon D, Pardo LA, Robertson GA, Rudy B, Sanguinetti MC, Stuhmer W, Wang X (2005). "International Union of Pharmacology. LIII. Nomenclature and molecular relationships of voltage-gated potassium channels.". Pharmacol Rev 57 (4): 473–508. doi:10.1124/pr.57.4.10. PMID 16382104.
^ Pongs O, Leicher T, Berger M, Roeper J, Bahring R, Wray D, Giese KP, Silva AJ, Storm JF (1999). "Functional and molecular aspects of voltage-gated K⁺ channel beta subunits". Ann N Y Acad Sci 868 (Apr 30): 344–55. doi:10.1111/j.1749-6632.1999.tb11296.x. PMID 10414304.
^ Li Y, Um SY, McDonald TV (2006). "Voltage-gated potassium channels: regulation by accessory subunits". Neuroscientist 12 (3): 199–210. doi:10.1177/1073858406287717. PMID 16684966.
^ Zhang M, Jiang M, Tseng GN (2001). "minK-related peptide 1 associates with Kv4.2 and modulates its gating function: potential role as beta subunit of cardiac transient outward channel?". Circ Res 88 (10): 1012–9. doi:10.1161/hh1001.090839. PMID 11375270.
^ McCrossan ZA, Abbott GW (2004). "The MinK-related peptides". Neuropharmacology 47 (6): 787–821. doi:10.1016/j.neuropharm.2004.06.018. PMID 15527815.
^ Anantharam A, Abbott GW (2005). "Does hERG coassemble with a beta subunit? Evidence for roles of MinK and MiRP1". Novartis Found Symp 266 (42): 112–7, 155–8. doi:10.1002/047002142X.fmatter. PMID 16050264.
^ Long SB, Campbell EB, Mackinnon R (2005). "Crystal structure of a mammalian voltage-dependent Shaker family K+ channel". Science 309 (5736): 897–903. doi:10.1126/science.1116269. PMID 16002581.
^ Lee S, Lee A, Chen J, MacKinnon R (2005). "Structure of the KvAP voltage-dependent K+ channel and its dependence on the lipid membrane.". Proc Natl Acad Sci USA 102 (43): 15441–6. doi:10.1073/pnas.0507651102. PMC 1253646. PMID 16223877.
^ Armstrong CM, Bezanilla F (April 1973). "Currents related to movement of the gating particles of the sodium channels". Nature 242 (5398): 459–61. doi:10.1038/242459a0. PMID 4700900.
^ Murrell-Lagnado RD, Aldrich RW (December 1993). "Energetics of Shaker K channels block by inactivation peptides". J. Gen. Physiol. 102 (6): 977–1003. doi:10.1085/jgp.102.6.977. PMC 2229186. PMID 8133246.

External links

Voltage-Gated Potassium Channels at the US National Library of Medicine Medical Subject Headings (MeSH)
"Voltage-Gated Potassium Channels". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology.
Li B, Gallin W (2004). "VKCDB: voltage-gated potassium channel database.". BMC Bioinformatics 5: 3. doi:10.1186/1471-2105-5-3. PMC 317694. PMID 14715090.
"Voltage-gated potassium channel database (VKCDB)" at ualberta.ca
UMich Orientation of Proteins in Membranes families/superfamily-8 - Spatial positions of voltage gated potassium channels in membranes

UpToDate Contents

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2. 赤血球水分量の制御 control of red blood cell hydration
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5. 心筋活動電位および抗不整脈剤の作用 myocardial action potential and action of antiarrhythmic drugs

English Journal

Effects of deletion and insertion of amino acids on the activity of HelaTx1, a scorpion toxin on potassium channels.

Peigneur S1, Esaki N2, Yamaguchi Y2, Tytgat J1, Sato K3.
Toxicon : official journal of the International Society on Toxinology.Toxicon.2016 Mar 1;111:1-5. doi: 10.1016/j.toxicon.2015.12.014. Epub 2015 Dec 24.
Four analogs of HelaTx1, a 25-mer peptide from scorpion venom, were synthesized by deleting its C-terminal hexapeptide fragment and N-terminal Ser residue and by inserting an amino acid in the middle part of the molecule. CD spectrum of HelaTx1(1-19) was almost superimposable to that of native HelaT
PMID 26724500

The Sensorless Pore Module of Voltage-gated K+ Channel Family 7 Embodies the Target Site for the Anticonvulsant Retigabine.

Syeda R1, Santos JS1, Montal M2.
The Journal of biological chemistry.J Biol Chem.2016 Feb 5;291(6):2931-7. doi: 10.1074/jbc.M115.683185. Epub 2015 Dec 1.
KCNQ (voltage-gated K(+) channel family 7 (Kv7)) channels control cellular excitability and underlie the K(+) current sensitive to muscarinic receptor signaling (the M current) in sympathetic neurons. Here we show that the novel anti-epileptic drug retigabine (RTG) modulates channel function of pore
PMID 26627826

Characterization of relaxant mechanism of H2 S in mouse corpus cavernosum.

Aydinoglu F1, Ogulener N2.
Clinical and experimental pharmacology & physiology.Clin Exp Pharmacol Physiol.2016 Feb 4. doi: 10.1111/1440-1681.12554. [Epub ahead of print]
The aim of this study was to investigate the mechanism of H2 S-induced relaxation in mouse corpus cavernosal tissue. L-cysteine (10-6 -3x10-3 M) and exogenous H2 S (NaHS; 10-6 -10-3 M) induced concentration-dependent relaxation. L-cysteine-induced relaxations was reduced by D,L-propargylglycine, a c
PMID 26845078

Japanese Journal

電位依存性プロトンチャネルにおけるプロトン透過の機構

生物物理 56(3), 154-158, 2016-06
NAID 40020877630

研究・症例ランバート・イートン筋無力症候群と傍腫瘍性小脳変性症を伴った小細胞肺癌の1例

日本胸部臨床 75(4), 438-444, 2016-04
NAID 40020803101

18. 抗Voltage-Gated Potassium Channel複合体抗体関連辺縁系脳炎の関与が考えられた成人発症内側側頭葉てんかんの1例(第33回産業医科大学学会総会学術講演・展示抄録集)

産業医科大学雑誌 38(1), 92, 2016-03-01
NAID 110010039769

Related Pictures

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関連記事	「channel」「voltage」「k」「Kd」「K channel」

「channel」

Ion channel (bacterial)
	; Potassium channel KcsA. Calculated hydrocarbon boundaries of the lipid bilayer are indicated by red and blue dots.
Identifiers
Symbol	Ion_trans_2
Pfam	PF07885
InterPro	IPR013099
SCOP	1bl8
SUPERFAMILY	1bl8
OPM protein	1r3j
Available protein structures:
Pfam	structures
PDB	RCSB PDB; PDBe
PDBsum	structure summary

Available protein structures:
Pfam	structures
PDB	RCSB PDB; PDBe
PDBsum	structure summary

Ion channel (eukaryotic)
	; Potassium channel, structure in a membrane-like environment. Calculated hydrocarbon boundaries of the lipid bilayer are indicated by red and blue dots.
Identifiers
Symbol	Ion_trans
Pfam	PF00520
InterPro	IPR005821
SCOP	1bl8
SUPERFAMILY	1bl8
TCDB	1.A.1
OPM superfamily	8
OPM protein	2a79
Available protein structures:
Pfam	structures
PDB	RCSB PDB; PDBe
PDBsum	structure summary