voltage-gated potassium channel

• 電位開口型カリウムチャネル、電位開口型K+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 K+ channel

WordNet

1. direct the flow of; "channel information towards a broad audience" (同)canalize, canalise
2. 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
3. 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"
4. (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
5. a path over which electrical signals can pass; "a channel is typically what you rent from a telephone company" (同)transmission channel
6. 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"
7. supply with a gate; "The house was gated"
8. restrict (school boys'
9. total admission receipts at a sports event
10. a computer circuit with several inputs but only one output that can be activated by particular combinations of inputs (同)logic gate
11. a movable barrier in a fence or wall
12. passageway (as in an air terminal) where passengers can embark or disembark
13. control with a valve or other device that functions like a gate
14. a light soft silver-white metallic element of the alkali metal group; oxidizes rapidly in air and reacts violently with water; is abundant in nature in combined forms occurring in sea water and in carnallite and kainite and sylvite (同)K, atomic number 19
15. 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
16. a gangsters pistol (同)rod

PrepTutorEJDIC

1. 〈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
2. (…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
3. ポタシウム,カリウム(金属元素;化学記号はK)
4. 電圧,電圧量,ボルト数
5. ピストル,はじき

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2017/01/11 21:45:38」(JST)

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[Wiki en表示]

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; PDBj PDBsum structure summary

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; PDBj PDBsum structure summary

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; PDBj 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; PDBj PDBsum structure summary

Kv2 voltage-gated K+ channel
Identifiers
Symbol	Kv2channel
Pfam	PF03521
InterPro	IPR003973
Available protein structures: Pfam structures PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

Voltage-gated potassium channels (VGKCs) 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.

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. 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)

Inwardly-rectifying

Passes current more easily in the inward direction (into the cell, from outside).

• 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. These subunits do not conduct current on their own but rather modulate the activity of K_v channels.

• K_vβ1 (KCNAB1)
• K_vβ2 (KCNAB2)
• K_vβ3 (KCNAB3)
• minK (KCNE1)
• MiRP1 (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.

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​), 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-[YF]-Gly sequences from the four channel subunits [1].

It may seem counterintuitive that a channel should 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

The structure of the mammalian voltage-gated K⁺ channel has been used to explain its ability to respond to the voltage across the membrane. Upon opening of the channel, conformational changes in the voltage-sensor domains (VSD) result in the transfer of 12-13 elementary charges across the membrane electric field. This charge transfer is measured as a transient capacitive current that precedes opening of the channel. Several charged residues of the VSD, in particular four arginine residues located regularly at every third position on the S4 segment, are known to move across the transmembrane field and contribute to the gating charge. The position of these arginines, known as gating arginines, are highly conserved in all voltage-gated potassium, sodium, or calcium channels. However, the extent of their movement and their displacement across the transmembrane potential has been subject to extensive debate. Specific domains of the channel subunits have been identified that are responsible for voltage-sensing and converting between the open and closed conformations of the channel. There are at least two closed conformations. In the first, the channel can open if the membrane potential becomes more positive. This type of gating is mediated by a voltage-sensing domain that consists of the S4 alpha helix that contains 6–7 positive charges. Changes in membrane potential cause this alpha helix to move in the lipid bilayer. This movement in turn results in a conformational change in the adjacent S5–S6 helices that form the channel pore and cause this pore to open or close. In the second, "N-type" inactivation, voltage-gated K⁺ channels inactivate after opening, entering a distinctive, closed conformation. In this 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 mechanism of this type of inactivation 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 blocks the inner porehole, preventing ion movement through the channel.

See also

• Ion channel
• Potassium channel tetramerisation domain
• Ion channel family
• Guangxitoxin

References

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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English Journal

• VEGF attenuated increase of outward delayed-rectifier potassium currents in hippocampal neurons induced by focal ischemia via PI3-K pathway.

• Wu KW1, Yang P2, Li SS2, Liu CW2, Sun FY3.
• Neuroscience.Neuroscience.2015 Jul 9;298:94-101. doi: 10.1016/j.neuroscience.2015.04.015. Epub 2015 Apr 12.
• We recently indicated that the vascular endothelial growth factor (VEGF) protects neurons against hypoxic death via enhancement of tyrosine phosphorylation of Kv1.2, an isoform of the delayed-rectifier potassium channels through activation of the phosphatidylinositol 3-kinase (PI3-K) signaling pathw
• PMID 25872187

• Biophysical characterization of KV3.1 potassium channel activating compounds.

• Taskin B1, von Schoubye NL2, Sheykhzade M3, Bastlund JF4, Grunnet M5, Jespersen T6.
• European journal of pharmacology.Eur J Pharmacol.2015 Jul 5;758:164-70. doi: 10.1016/j.ejphar.2015.03.061. Epub 2015 Apr 3.
• The effect of two positive modulators, RE1 and EX15, on the voltage-gated K(+) channel Kv3.1 was investigated using the whole-cell patch-clamp technique on HEK293 cells expressing Kv3.1a. RE1 and EX15 increased the Kv3.1 currents in a concentration-dependent manner with an EC50 value of 4.5 and 1.3�
• PMID 25845309

• Arecoline inhibits intermediate-conductance calcium-activated potassium channels in human glioblastoma cell lines.

• So EC1, Huang YM2, Hsing CH3, Liao YK2, Wu SN4.
• European journal of pharmacology.Eur J Pharmacol.2015 Jul 5;758:177-87. doi: 10.1016/j.ejphar.2015.03.065. Epub 2015 Apr 2.
• Arecoline (ARE) is an alkaloid-type natural product from areca nut. This compound has numerous pharmacological and toxicological effects. Whether this agent interacts with ion channels to perturb functional activity of cells remains unknown. The effects of ARE on ionic currents were studied in gliom
• PMID 25843414

Japanese Journal

• Oral Administration of Apple Procyanidins Ameliorates Insulin Resistance via Suppression of Pro-inflammatory Cytokines Expression in Liver of Diabetic ob/ob Mice

• Journal of Agricultural and Food Chemistry 64(46), 8857-8865, 2016-11-23
• NAID 120005893547

• VGKC複合体抗体関連脳症とその周辺疾患 (特集 自己免疫性脳炎・脳症)

• Brain and nerve 68(9), 1011-1023, 2016-09
• NAID 40020964444

• 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 Links

• Voltage-gated potassium channel - an overview ...

Voltage-gated potassium channel Voltage-gated potassium channels (KV) are a large group of channels supporting K+ efflux when they open in response to membrane depolarization. From: Ion Channels in Health and Disease, 2016

• Voltage-gated potassium channels | Ion channels | IUPHAR ...

The 6TM family of K channels comprises the voltage-gated K V subfamilies, the EAG subfamily (which includes hERG channels), the Ca 2+-activated Slo subfamily (actually with 7TM, termed BK) and the Ca 2+-activated SK ...

Related Pictures

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★リンクテーブル★

リンク元	「電位依存性K+チャネル」「voltage-gated K+ channel」「voltage-dependent potassium channel」「電位開口型K+チャネル」「電位開口型カリウムチャネル」
関連記事	「channel」「voltage」「gate」

「電位依存性K+チャネル」

　　[★]

英

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

関

電位依存性カリウムチャネル、電位開口型カリウムチャネル、電位開口型K+チャネル

「voltage-gated K+ channel」

　　[★]

• 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

「voltage-dependent potassium channel」

　　[★]

• 電位依存性カリウムチャネル、電位依存性K+チャネル

関

Kv channel、voltage-dependent K+ channel、voltage-gated K+ channel、voltage-gated potassium channel

「電位開口型K+チャネル」

　　[★]

英

voltage-gated potassium channel、voltage-gated K+ channel

関

電位開口型カリウムチャネル、電位依存性K+チャネル

「電位開口型カリウムチャネル」

　　[★]

英

voltage-gated potassium channel、voltage-gated K+ channel

関

電位依存性K+チャネル、電位開口型K+チャネル

「channel」

　　[★]

• n.

• 川床、川底。水路、河道
• 海峡
• 水管、導管
• 溝
• 経路、ルート。道筋、方向

• チャネル、チャンネル、イオンチャネル

関

ion channel、ionic channel

　 　 　 　 　 　 　

「voltage」

　　[★]

• n.

• 電位、ボルテージ

関

electric potential、electrical potential、potential

　 　

「gate」

　　[★]