KCNN2

Potassium channel, calcium activated intermediate/small conductance subfamily N alpha, member 2

PDB rendering based on 1g4y.

Available structures

Ortholog search: PDBe, RCSB

List of PDB id codes
1g4y, 1kkd, 1qx7

Identifiers

Symbols

KCNN2 ; KCa2.2; SK2; SKCA2; SKCa 2; hSK2

External IDs

OMIM: 605879 MGI: 2153182 HomoloGene: 23150 IUPHAR: 382 ChEMBL: 4469 GeneCards: KCNN2 Gene

Gene ontology
Molecular function	• calmodulin binding • calcium-activated potassium channel activity • small conductance calcium-activated potassium channel activity • protein domain specific binding • protein homodimerization activity • alpha-actinin binding
Cellular component	• smooth endoplasmic reticulum • plasma membrane • cell surface • integral component of membrane • Z disc • T-tubule • neuronal cell body • dendritic spine
Biological process	• potassium ion transport • synaptic transmission • potassium ion transmembrane transport • regulation of potassium ion transmembrane transport
Sources: Amigo / QuickGO

RNA expression pattern

More reference expression data

Orthologs

Species

Human

Mouse

RefSeq (mRNA)

RefSeq (protein)

Location (UCSC)

Chr 5:
114.36 – 114.5 Mb

Chr 18:
45.27 – 45.69 Mb

PubMed search

Potassium intermediate/small conductance calcium-activated channel, subfamily N, member 2, also known as KCNN2, is a protein which in humans is encoded by the KCNN2 gene.^[1] KCNN2 is an ion channel protein also known as K_Ca2.2.^[2]

Function

Action potentials in vertebrate neurons are followed by an afterhyperpolarization (AHP) that may persist for several seconds and may have profound consequences for the firing pattern of the neuron. Each component of the AHP is kinetically distinct and is mediated by different calcium-activated potassium channels. The K_Ca2.2 protein is activated before membrane hyperpolarization and is thought to regulate neuronal excitability by contributing to the slow component of synaptic AHP. K_Ca2.2 is an integral membrane protein that forms a voltage-independent calcium-activated channel with three other calmodulin-binding subunits. This protein is a member of the calcium-activated potassium channel family. Two transcript variants encoding different isoforms have been found for the KCNN2 gene.^[2]

In a study SK2 (KCNN2) potassium channel was overexpressed in the basolateral amygdala using a herpes simplex viral system. This reduced anxiety and stress-induced corticosterone secretion at a systemic level. SK2 overexpression also reduced dendritic arborization of the amygdala neurons.^[3]

References

↑ Wei AD, Gutman GA, Aldrich R, Chandy KG, Grissmer S, Wulff H (December 2005). "International Union of Pharmacology. LII. Nomenclature and molecular relationships of calcium-activated potassium channels". Pharmacol. Rev. 57 (4): 463–72. doi:10.1124/pr.57.4.9. PMID 16382103.
1 2 "Entrez Gene: KCNN2 potassium intermediate/small conductance calcium-activated channel, subfamily N, member 2".
↑ Mitra R, Ferguson D, Sapolsky RM (February 2009). "SK2 potassium channel over-expression in basolateral amygdala reduces anxiety, stress-induced corticosterone and dendritic arborization". Mol. Psychiatry 14 (9): 847–55, 827. doi:10.1038/mp.2009.9. PMC 2763614. PMID 19204724.

Wei AD, Gutman GA, Aldrich R, et al. (2006). "International Union of Pharmacology. LII. Nomenclature and molecular relationships of calcium-activated potassium channels". Pharmacol. Rev. 57 (4): 463–72. doi:10.1124/pr.57.4.9. PMID 16382103.
Jäger H, Adelman JP, Grissmer S (2000). "SK2 encodes the apamin-sensitive Ca²⁺-activated K⁺ channels in the human leukemic T cell line, Jurkat". FEBS Lett. 469 (2–3): 196–202. doi:10.1016/S0014-5793(00)01236-9. PMID 10713270.
Liu QH, Williams DA, McManus C, et al. (2000). "HIV-1 gp120 and chemokines activate ion channels in primary macrophages through CCR5 and CXCR4 stimulation". Proc. Natl. Acad. Sci. U.S.A. 97 (9): 4832–7. doi:10.1073/pnas.090521697. PMC 18318. PMID 10758170.
Desai R, Peretz A, Idelson H, et al. (2001). "Ca²⁺-activated K⁺ channels in human leukemic Jurkat T cells. Molecular cloning, biochemical and functional characterization". J. Biol. Chem. 275 (51): 39954–63. doi:10.1074/jbc.M001562200. PMID 10991935.
Rimini R, Rimland JM, Terstappen GC (2001). "Quantitative expression analysis of the small conductance calcium-activated potassium channels, SK1, SK2 and SK3, in human brain". Brain Res. Mol. Brain Res. 85 (1–2): 218–20. doi:10.1016/S0169-328X(00)00255-2. PMID 11146124.
Schumacher MA, Rivard AF, Bächinger HP, Adelman JP (2001). "Structure of the gating domain of a Ca²⁺-activated K⁺ channel complexed with Ca²⁺/calmodulin". Nature 410 (6832): 1120–4. doi:10.1038/35074145. PMID 11323678.
Miller MJ, Rauer H, Tomita H, et al. (2001). "Nuclear localization and dominant-negative suppression by a mutant SKCa3 N-terminal channel fragment identified in a patient with schizophrenia". J. Biol. Chem. 276 (30): 27753–6. doi:10.1074/jbc.C100221200. PMID 11395478.
Strausberg RL, Feingold EA, Grouse LH, et al. (2003). "Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences". Proc. Natl. Acad. Sci. U.S.A. 99 (26): 16899–903. doi:10.1073/pnas.242603899. PMC 139241. PMID 12477932.
Piotrowska AP, Solari V, Puri P (2003). "Distribution of Ca²⁺-activated K channels, SK2 and SK3, in the normal and Hirschsprung's disease bowel". J. Pediatr. Surg. 38 (6): 978–83. doi:10.1016/S0022-3468(03)00138-6. PMID 12778407.
Xu Y, Tuteja D, Zhang Z, et al. (2004). "Molecular identification and functional roles of a Ca²⁺-activated K⁺ channel in human and mouse hearts". J. Biol. Chem. 278 (49): 49085–94. doi:10.1074/jbc.M307508200. PMID 13679367.
Ota T, Suzuki Y, Nishikawa T, et al. (2004). "Complete sequencing and characterization of 21,243 full-length human cDNAs". Nat. Genet. 36 (1): 40–5. doi:10.1038/ng1285. PMID 14702039.
Feranchak AP, Doctor RB, Troetsch M, et al. (2004). "Calcium-dependent regulation of secretion in biliary epithelial cells: the role of apamin-sensitive SK channels". Gastroenterology 127 (3): 903–13. doi:10.1053/j.gastro.2004.06.047. PMID 15362045.
Tajima N, Schönherr K, Niedling S, et al. (2006). "Ca²⁺-activated K⁺ channels in human melanoma cells are up-regulated by hypoxia involving hypoxia-inducible factor-1α and the von Hippel-Lindau protein". J. Physiol. (Lond.) 571 (Pt 2): 349–59. doi:10.1113/jphysiol.2005.096818. PMC 1796787. PMID 16396931.
Lu L, Zhang Q, Timofeyev V, et al. (2007). "Molecular coupling of a Ca²⁺-activated K⁺ channel to L-type Ca²⁺ channels via alpha-actinin2". Circ. Res. 100 (1): 112–20. doi:10.1161/01.RES.0000253095.44186.72. PMID 17110593.
Morimoto T, Ohya S, Hayashi H, et al. (2007). "Cell-cycle-dependent regulation of Ca²⁺-activated K⁺ channel in Jurkat T-lymphocyte". J. Pharmacol. Sci. 104 (1): 94–8. doi:10.1254/jphs.SC0070032. PMID 17452806.
Dolga AM, Terpolilli N, Kepura F, et al. (2011). "KCa2 channels activation prevents [Ca²⁺]i deregulation and reduces neuronal death following glutamate toxicity and cerebral ischemia". Cell Death Dis. 2 (e147). doi:10.1038/cddis.2011.30. PMC 3122061. PMID 21509037.

This article incorporates text from the United States National Library of Medicine, which is in the public domain.

PDB gallery

1g4y: 1.60 A CRYSTAL STRUCTURE OF THE GATING DOMAIN FROM SMALL CONDUCTANCE POTASSIUM CHANNEL COMPLEXED WITH CALCIUM-CALMODULIN

1kkd: Solution structure of the calmodulin binding domain (CaMBD) of small conductance Ca2+-activated potassium channels (SK2)

1qx7: Crystal structure of apoCaM bound to the gating domain of small conductance Ca2+-activated potassium channel

Membrane transport protein: ion channels (TC 1A)

Ca²⁺: Calcium channel

Ligand-gated	Inositol trisphosphate receptor 1 2 3 Ryanodine receptor 1 2 3

Voltage-gated	L-type/Ca_vα 1.1 1.2 1.3 1.4 N-type/Ca_vα2.2 P-type/Ca_vα 2.1 Q-type/Ca_vα2.1 R-type/Ca_vα2.3 T-type/Ca_vα 3.1 3.2 3.3 α₂δ-subunits 1 2 β-subunits β1 β2 β3 β4 γ-subunits γ1 γ2 γ3 γ4 Cation channels of sperm 1 2 3 4 Two-pore channel 1 2

Na⁺: Sodium channel

Constitutively active	Epithelial sodium channel α β γ δ

Proton-gated	Amiloride-sensitive cation channel 1 2 3 4

Voltage-gated	Na_vα 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 7A Na_vβ 1 2 3 4

K⁺: Potassium channel

Calcium-activated	BK channel α1 β1 β2 β3 β4 SK channel SK1 SK2 SK3 IK channel IK1 K_Ca 1.1 2.1 2.2 2.3 3.1 4.1 4.2 5.1

Inward-rectifier	K_ATP K_ir 1.1 2.1 2.2 2.3 2.4 2.6 GIRK/K_ir 3.1 3.2 3.3 3.4 K_ir 4.1 4.2 5.1 6.1 6.2 7.1

Tandem pore domain	K2P 1 2 3 4 5 6 7 9 10 12 13 15 16 17 18

Voltage-gated	K_vα1-6 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 2.1 2.2 3.1 3.2 3.3 3.4 4.1 4.2 4.3 5.1 6.1 6.2 6.3 6.4 K_vα7-12 7.1 7.2 7.3 7.4 7.5 8.1 8.2 9.1 9.2 9.3 10.1 10.2 11.1/hERG 11.2 11.3 12.1 12.2 12.3 K_vβ 1 2 3 KCNIP 1 2 3 4 minK/ISK minK/ISK-like MiRP 1 2 3 Shaker gene

Miscellaneous

Cl⁻: Chloride channel	Calcium-activated chloride channels Anoctamin ANO1 Bestrophin 1 2 Chloride Channel Accessory 1 2 3 4 CFTR CLCN 1 2 3 4 5 6 7 KA KB CLIC 1 2 3 4 5 6 L1 CLNS 1A 1B

H⁺: Proton channel	HVCN1

M⁺: CNG cation channel	α 1 2 3 4 β 1 2 3 HCN FC 1 2 3 4

M⁺: TRP cation channel	TRPA (1) TRPC 1 2 3 4 4AP 5 6 7 TRPM 1 2 3 4 5 6 7 8 TRPML 1 2 3 TRPN TRPP 1 2 TRPV 1 2 3 4 5 6

H₂O (+ solutes): Porin	Aquaporin 0 1 2 3 4 5 6 7 8 9 Voltage-dependent anion channel 1 2 3 General bacterial porin family

Cytoplasm: Gap junction	Connexin: A GJA1 GJA3 GJA4 GJA5 GJA8 GJA9 GJA10 B GJB1 GJB2 GJB3 GJB4 GJB5 GJB6 GJB7 C GJC1 GJC2 GJC3 D GJD2 GJD3 GJD4) Innexin

By gating mechanism

Ion channel class	Ligand-gated Light-gated Voltage-gated Stretch-activated

see also disorders

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KCNN2

Function

See also

References

Further reading