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Potassium voltage-gated channel subfamily A member 2



Rattus norvegicus (Rat)
Reviewed-Annotation score: -Experimental evidence at protein leveli


Voltage-gated potassium channel that mediates transmembrane potassium transport in excitable membranes, primarily in the brain and the central nervous system, but also in the cardiovascular system. Prevents aberrant action potential firing and regulates neuronal output. Forms tetrameric potassium-selective channels through which potassium ions pass in accordance with their electrochemical gradient. The channel alternates between opened and closed conformations in response to the voltage difference across the membrane (PubMed:12151401, PubMed:21602278, PubMed:24472174). Can form functional homotetrameric channels and heterotetrameric channels that contain variable proportions of KCNA1, KCNA2, KCNA4, KCNA5, KCNA6, KCNA7, and possibly other family members as well; channel properties depend on the type of alpha subunits that are part of the channel (PubMed:8495559, PubMed:15618540, PubMed:20805574, PubMed:23725331). Channel properties are modulated by cytoplasmic beta subunits that regulate the subcellular location of the alpha subunits and promote rapid inactivation of delayed rectifier potassium channels (PubMed:18003609, PubMed:19713757). In vivo, membranes probably contain a mixture of heteromeric potassium channel complexes, making it difficult to assign currents observed in intact tissues to a particular potassium channel family member. Homotetrameric KCNA2 forms a delayed-rectifier potassium channel that opens in response to membrane depolarization, followed by slow spontaneous channel closure (PubMed:1715584, PubMed:16770729, PubMed:17766348, PubMed:18003609, PubMed:18638484, PubMed:19713757, PubMed:20089912). In contrast, a heteromultimer formed by KCNA2 and KCNA4 shows rapid inactivation (PubMed:8495559). Response to toxins that are selective for KCNA1, respectively for KCNA2, suggests that heteromeric potassium channels composed of both KCNA1 and KCNA2 play a role in pacemaking and regulate the output of deep cerebellar nuclear neurons (PubMed:23318870). KCNA2-containing channels play a presynaptic role and prevent hyperexcitability and aberrant action potential firing (PubMed:12777451). Response to toxins that are selective for KCNA2-containing potassium channels suggests that in Purkinje cells, dendritic subthreshold KCNA2-containing potassium channels prevent random spontaneous calcium spikes, suppressing dendritic hyperexcitability without hindering the generation of somatic action potentials, and thereby play an important role in motor coordination (PubMed:16210348). Plays a role in the induction of long-term potentiation of neuron excitability in the CA3 layer of the hippocampus (By similarity). May function as down-stream effector for G protein-coupled receptors and inhibit GABAergic inputs to basolateral amygdala neurons (PubMed:16306173). May contribute to the regulation of neurotransmitter release, such as gamma-aminobutyric acid (GABA) (PubMed:17869444). Contributes to the regulation of the axonal release of the neurotransmitter dopamine (PubMed:21647367). Reduced KCNA2 expression plays a role in the perception of neuropathic pain after peripheral nerve injury, but not acute pain (PubMed:24472174). Plays a role in the regulation of the time spent in non-rapid eye movement (NREM) sleep (By similarity).By similarityCurated20 Publications


The delay or D-type current observed in hippocampus pyramidal neurons is probably mediated by potassium channels containing KCNA2 plus KCNA1 or other family members. It is activated at about -50 mV, i.e. below the action potential threshold, and is characterized by slow inactivation, extremely slow recovery from inactivation, sensitivity to dendrotoxin (DTX) and to 4-aminopyridine (4-AP).1 Publication

Activity regulationi

Inhibited by 4-aminopyridine (4-AP), dendrotoxin (DTX) and charybdotoxin (CTX), but not by tetraethylammonium (TEA) (PubMed:2555158, PubMed:8495559, PubMed:18638484). Inhibited by tityustoxin-K alpha (TsTX-Kalpha), a toxin that is highly specific for KCNA2 (PubMed:8355670). Inhibited by maurotoxin (PubMed:24472174). Inhibited by kappaM conotoxins kappaM-RIIIJ and kappaM-RIIIK (By similarity).By similarity6 Publications


Homotetrameric channels activate rapidly, i.e within a few msec, but inactivation is very slow, with only a marginal decrease in conductance over several seconds. The voltage-dependence of activation and inactivation and other channel characteristics vary depending on the experimental conditions, the expression system, post-translational modifications and the presence or absence of ancillary subunits. For the activation of homotetrameric channels expressed in xenopus oocytes, the voltage at half-maximal amplitude is about -34 mV (PubMed:2555158). Unit channel conductance is about 10 pS (PubMed:2555158). For the activation of homotetrameric channels expressed in Chinese hamster ovary (CHO) cells, the voltage at half-maximal amplitude is about -10 mV (PubMed:17324383).2 Publications


      Feature keyPosition(s)DescriptionActionsGraphical viewLength
      Sitei252Important for normal, slow channel gating1 Publication1
      Sitei381Important for binding with the scorpion mesomartoxin; when the scorpion mesomartoxin-rKv1.2/KCNA2 interaction is modeled, this residue is close to the 'Y-57' residue of the toxin1 Publication1

      GO - Molecular functioni

      • delayed rectifier potassium channel activity Source: UniProtKB
      • kinesin binding Source: RGD
      • outward rectifier potassium channel activity Source: RGD
      • voltage-gated potassium channel activity Source: UniProtKB

      GO - Biological processi


      Molecular functionIon channel, Potassium channel, Voltage-gated channel
      Biological processIon transport, Potassium transport, Transport

      Enzyme and pathway databases

      ReactomeiR-RNO-1296072 Voltage gated Potassium channels

      Names & Taxonomyi

      Protein namesi
      Recommended name:
      Potassium voltage-gated channel subfamily A member 2
      Alternative name(s):
      RBK21 Publication
      RCK51 Publication
      Voltage-gated potassium channel subunit Kv1.2
      Gene namesi
      OrganismiRattus norvegicus (Rat)
      Taxonomic identifieri10116 [NCBI]
      Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresGliresRodentiaMyomorphaMuroideaMuridaeMurinaeRattus
      • UP000002494 Componenti: Chromosome 2

      Organism-specific databases

      RGDi2950 Kcna2

      Subcellular locationi

      Extracellular region or secreted Cytosol Plasma membrane Cytoskeleton Lysosome Endosome Peroxisome ER Golgi apparatus Nucleus Mitochondrion Manual annotation Automatic computational assertionGraphics by Christian Stolte; Source: COMPARTMENTS


      Feature keyPosition(s)DescriptionActionsGraphical viewLength
      Topological domaini1 – 160Cytoplasmic3 PublicationsAdd BLAST160
      Transmembranei161 – 182Helical; Name=Segment S13 PublicationsAdd BLAST22
      Topological domaini183 – 221Extracellular1 Publication3 PublicationsAdd BLAST39
      Transmembranei222 – 243Helical; Name=Segment S23 PublicationsAdd BLAST22
      Topological domaini244 – 254Cytoplasmic3 PublicationsAdd BLAST11
      Transmembranei255 – 275Helical; Name=Segment S32 PublicationsAdd BLAST21
      Topological domaini276 – 289Extracellular3 PublicationsAdd BLAST14
      Transmembranei290 – 310Helical; Voltage-sensor; Name=Segment S42 PublicationsAdd BLAST21
      Topological domaini311 – 325Cytoplasmic3 PublicationsAdd BLAST15
      Transmembranei326 – 347Helical; Name=Segment S53 PublicationsAdd BLAST22
      Topological domaini348 – 361Extracellular3 PublicationsAdd BLAST14
      Intramembranei362 – 373Helical; Name=Pore helix3 PublicationsAdd BLAST12
      Intramembranei374 – 3813 Publications8
      Topological domaini382 – 388Extracellular3 Publications7
      Transmembranei389 – 417Helical; Name=Segment S63 PublicationsAdd BLAST29
      Topological domaini418 – 499CytoplasmicCurated1 PublicationAdd BLAST82

      Keywords - Cellular componenti

      Cell junction, Cell membrane, Cell projection, Endoplasmic reticulum, Endosome, Membrane, Synapse, Synaptosome

      Pathology & Biotechi


      Feature keyPosition(s)DescriptionActionsGraphical viewLength
      Mutagenesisi34R → L: No effect on channel opening. 1 Publication1
      Mutagenesisi38N → A: Alters voltage-sensitive channel opening. 1 Publication1
      Mutagenesisi40S → A: No effect on channel opening. 1 Publication1
      Mutagenesisi41G → A: Loss of channel activity. 1 Publication1
      Mutagenesisi42L → A: No effect on channel opening. 1 Publication1
      Mutagenesisi43R → L: No effect on channel opening. 1 Publication1
      Mutagenesisi44F → A: Alters voltage-sensitive channel opening. 1 Publication1
      Mutagenesisi45E → A: Loss of channel activity. 1 Publication1
      Mutagenesisi46T → D: Impairs protein folding. Loss of tetramerization. 1 Publication1
      Mutagenesisi46T → V or A: No effect on tetramerization. Alters voltage-sensitive channel opening. 1 Publication1
      Mutagenesisi46T → V: Abolishes interaction with KCNAB2 and strongly reduces cell surface expression. No effect phosphorylation in response to increased cAMP levels. 1 Publication1
      Mutagenesisi47Q → A: No effect on channel opening. 1 Publication1
      Mutagenesisi50T → A: Alters voltage-sensitive channel opening. 1 Publication1
      Mutagenesisi70D → A: No effect on channel opening. 1 Publication1
      Mutagenesisi73R → A: No effect on channel opening. 1 Publication1
      Mutagenesisi75E → A: No effect on channel opening. 1 Publication1
      Mutagenesisi77F → W: Alters voltage-sensitive channel opening. 1 Publication1
      Mutagenesisi79D → N: Alters voltage-sensitive channel opening. 1 Publication1
      Mutagenesisi81N → A: No effect on channel opening. 1 Publication1
      Mutagenesisi82R → A: Loss of channel activity. 1 Publication1
      Mutagenesisi86D → A: Alters voltage-sensitive channel opening. 1 Publication1
      Mutagenesisi89L → A: No effect on channel opening. 1 Publication1
      Mutagenesisi90Y → A: No effect on channel opening. 1 Publication1
      Mutagenesisi93Q → A: Loss of channel activity. 1 Publication1
      Mutagenesisi97R → A: No effect on channel opening. 1 Publication1
      Mutagenesisi99R → A: No effect on channel opening. 1 Publication1
      Mutagenesisi102V → T: Alters voltage-sensitive channel opening. 1 Publication1
      Mutagenesisi103N → A: No effect on channel opening. 1 Publication1
      Mutagenesisi105P → A: No effect on channel opening. 1 Publication1
      Mutagenesisi107D → A: Alters voltage-sensitive channel opening. 1 Publication1
      Mutagenesisi108I → A: No effect on channel opening. 1 Publication1
      Mutagenesisi111E → A: Alters voltage-sensitive channel opening. 1 Publication1
      Mutagenesisi207N → Q: Loss of glycosylation site. 1 Publication1
      Mutagenesisi252T → R: Changes channel gating from a predominantly slow mode to a much more rapid mode. 1 Publication1
      Mutagenesisi267 – 302FITLG…LVRVF → YVTIFLTESNKSVLQFQNVR RVVQIFRIM in paddle chimera; changes channel activation to less negative voltage values and renders the channel susceptible to inhibition by the spider toxin VsTx1. 1 PublicationAdd BLAST36
      Mutagenesisi356S → A: Impairs N-glycosylation and abolishes expression at the cell surface. 1 Publication1
      Mutagenesisi360S → A: No effect on N-glycosylation. Abolishes channel activity of the homotetramer, but retains channel activity in the presence of a beta subunit. 1 Publication1
      Mutagenesisi381V → Y: Confers sensitivity to inhibition by tetraethylammonium (TEA). 1 Publication1
      Mutagenesisi383T → A: Impairs N-glycosylation and abolishes expression at the cell surface. 1 Publication1
      Mutagenesisi415Y → F: Nearly abolishes interaction with CTTN; when associated with F-417. 1 Publication1
      Mutagenesisi417Y → F: Nearly abolishes interaction with CTTN; when associated with F-415. Strongly reduces channel activity. 1 Publication1
      Mutagenesisi440S → A: Strongly reduces cell surface expression. Abolishes phosphorylation in response to increased cAMP levels. 1 Publication1
      Mutagenesisi449S → A: Strongly reduces cell surface expression. Abolishes phosphorylation in response to increased cAMP levels. 1 Publication1
      Mutagenesisi458Y → A: Impairs clustering on axon membranes. 1 Publication1

      Chemistry databases


      PTM / Processingi

      Molecule processing

      Feature keyPosition(s)DescriptionActionsGraphical viewLength
      ChainiPRO_00000539751 – 499Potassium voltage-gated channel subfamily A member 2Add BLAST499

      Amino acid modifications

      Feature keyPosition(s)DescriptionActionsGraphical viewLength
      Glycosylationi207N-linked (GlcNAc...) asparagineSequence analysis1 Publication1
      Lipidationi244S-palmitoyl cysteineSequence analysis1
      Modified residuei429PhosphotyrosineBy similarity1
      Modified residuei434PhosphoserineBy similarity1
      Modified residuei440PhosphoserineCombined sources1 Publication1
      Modified residuei441PhosphoserineCombined sources1
      Modified residuei449Phosphoserine2 Publications1
      Modified residuei458Phosphotyrosine1 Publication1
      Modified residuei468PhosphoserineCombined sources1

      Post-translational modificationi

      Phosphorylated on tyrosine residues; phosphorylation increases in response to ischemia (PubMed:14713306). Phosphorylated on tyrosine residues by activated PTK2B/PYK2 (PubMed:7544443). Phosphorylation on tyrosine residues suppresses ion channel activity (PubMed:7544443). Phosphorylated on tyrosine residues in response to CHRM1 activation; this abolishes interaction with CTTN (PubMed:12151401). This is probably due to endocytosis of the phosphorylated channel subunits. Phosphorylated on serine residues in response to increased cAMP levels; phosphorylation is apparently not catalyzed by PKA (PubMed:18003609).4 Publications
      N-glycosylated, with complex, sialylated N-glycans.2 Publications

      Keywords - PTMi

      Glycoprotein, Lipoprotein, Palmitate, Phosphoprotein

      Proteomic databases


      PTM databases



      Tissue specificityi

      Detected in neurons in dorsal root ganglion (PubMed:24472174). Detected in hippocampus neurons (PubMed:21602278). Detected on neurons of the anteroventral cochlear nucleus (PubMed:12777451). Detected in renal arteries (PubMed:12632190). Detected in neurons of the medial nucleus of the trapezoid body (PubMed:12177193). Detected in neurons in the brain cortex (PubMed:14713306). Detected in axon tracts of the corpus callosum, specific terminal fields of the brain cortex neuropil, neurons in the medial entorhinal cortex, and in puncta representing mossy fiber terminals in the hippocampus mossy fiber tract; these puncta correspond to synapses made by dentate granule cells (PubMed:8361540). Detected in paranodal and juxtanodal zones in the central nervous system, including myelinated spinal cord (PubMed:11086297, PubMed:20089912). Detected in the juxtaparanodal region in optic nerve (PubMed:10624965). Detected at nerve terminal plexuses of basket cells in the cerebellum (at protein level) (PubMed:7477295, PubMed:20089912). Detected in brain (PubMed:2722779). Detected in heart atrium and ventricle (PubMed:1715584). Detected in renal arteries (PubMed:12632190).12 Publications


      Up-regulated in brain cortex in response to ischemia (at protein level) (PubMed:14713306). Down-regulated in dorsal root ganglion neurons after peripheral nerve injury (at protein level) (PubMed:24472174). Down-regulated in pulmonary artery myocytes in response to chronic moderate hypoxia.3 Publications

      Gene expression databases

      BgeeiENSRNOG00000018285 Expressed in 9 organ(s), highest expression level in brain
      ExpressionAtlasiP63142 baseline and differential
      GenevisibleiP63142 RN


      Subunit structurei

      Homotetramer and heterotetramer with other channel-forming alpha subunits, such as KCNA1, KCNA4, KCNA5, KCNA6 and KCNA7 (PubMed:8495559, PubMed:8361540, PubMed:10896669, PubMed:12777451, PubMed:12632190, PubMed:15618540, PubMed:11007484, PubMed:16002581, PubMed:18004376, PubMed:20534430). Channel activity is regulated by interaction with beta subunits, including KCNAB1 and KCNAB2 (PubMed:18003609, PubMed:19713757, PubMed:16002581, PubMed:18004376, PubMed:20534430, PubMed:20360102, PubMed:23705070). Identified in a complex with KCNA1 and KCNAB2 (PubMed:11086297, PubMed:23318870). Identified in a complex with KCNA5 and KCNAB1 (By similarity). Identified in a complex with KCNA4 and FYN (By similarity). Interacts (via C-terminus) with the PDZ domains of DLG1 and DLG2 (PubMed:7477295). Interacts with DLG4 (via PDZ domain) (PubMed:7477295, PubMed:20089912). Interacts with PTK2B (PubMed:11739373). Interacts (via C-terminus) with CTTN (PubMed:12151401). Interacts (via N-terminal cytoplasmic domain) with RHOA (GTP-bound form); this regulates channel activity by reducing location at the cell surface in response to CHRM1 activation (PubMed:9635436). Interacts with DRD2 (By similarity). Interacts with SIGMAR1; cocaine consumption leads to increased interaction (By similarity). Interacts with CNTNAP2 (PubMed:10624965). Interacts with ADAM22 (PubMed:20089912).By similarityCurated20 Publications

      Binary interactionsi

      DLG4P783522EBI-631446,EBI-80389From Homo sapiens.

      GO - Molecular functioni

      Protein-protein interaction databases

      BioGridi247501, 5 interactors
      IntActiP63142, 3 interactors


      Secondary structure

      Legend: HelixTurnBeta strandPDB Structure known for this area
      Show more details

      3D structure databases


      Miscellaneous databases


      Family & Domainsi


      Feature keyPosition(s)DescriptionActionsGraphical viewLength
      Regioni1 – 125Tetramerization domain1 PublicationAdd BLAST125
      Regioni312 – 325S4-S5 linker1 PublicationAdd BLAST14


      Feature keyPosition(s)DescriptionActionsGraphical viewLength
      Motifi374 – 379Selectivity filterCurated6
      Motifi497 – 499PDZ-binding1 Publication3


      The cytoplasmic N-terminus is important for tetramerization. Interactions between the different subunits modulate the gating characteristics (PubMed:11007484). Besides, the cytoplasmic N-terminal domain mediates interaction with RHOA and thus is required for RHOA-mediated endocytosis (PubMed:9635436).3 Publications
      The transmembrane segment S4 functions as voltage-sensor and is characterized by a series of positively charged amino acids at every third position. Channel opening and closing is effected by a conformation change that affects the position and orientation of the voltage-sensor paddle formed by S3 and S4 within the membrane. A transmembrane electric field that is positive inside would push the positively charged S4 segment outwards, thereby opening the pore, while a field that is negative inside would pull the S4 segment inwards and close the pore. Changes in the position and orientation of S4 are then transmitted to the activation gate formed by the inner helix bundle via the S4-S5 linker region.2 Publications

      Sequence similaritiesi

      Keywords - Domaini

      Transmembrane, Transmembrane helix

      Phylogenomic databases

      eggNOGiKOG1545 Eukaryota
      COG1226 LUCA

      Family and domain databases

      Gene3Di1.20.120.350, 1 hit
      InterProiView protein in InterPro
      IPR000210 BTB/POZ_dom
      IPR005821 Ion_trans_dom
      IPR003968 K_chnl_volt-dep_Kv
      IPR003972 K_chnl_volt-dep_Kv1
      IPR004049 K_chnl_volt-dep_Kv1.2
      IPR011333 SKP1/BTB/POZ_sf
      IPR003131 T1-type_BTB
      IPR028325 VG_K_chnl
      IPR027359 Volt_channel_dom_sf
      PANTHERiPTHR11537 PTHR11537, 1 hit
      PTHR11537:SF23 PTHR11537:SF23, 1 hit
      PfamiView protein in Pfam
      PF02214 BTB_2, 1 hit
      PF00520 Ion_trans, 1 hit
      PR01509 KV12CHANNEL
      PR01491 KVCHANNEL
      SMARTiView protein in SMART
      SM00225 BTB, 1 hit
      SUPFAMiSSF54695 SSF54695, 1 hit

      Sequence (1+)i

      Sequence statusi: Complete.

      This entry has 1 described isoform and 1 potential isoform that is computationally mapped.iShow all

      P63142-1 [UniParc]FASTAAdd to basket
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      Mass (Da):56,701
      Last modified:September 13, 2004 - v1

      Computationally mapped potential isoform sequencesi

      There is 1 potential isoform mapped to this entry.BLASTAlignShow allAdd to basket
      EntryEntry nameProtein names
      Gene namesLengthAnnotation
      Potassium voltage-gated channel sub...
      77Annotation score:

      Experimental Info

      Feature keyPosition(s)DescriptionActionsGraphical viewLength
      Sequence conflicti411S → F in AAA19867 (PubMed:1715584).Curated1

      Sequence databases

      Select the link destinations:
      Links Updated
      J04731 mRNA Translation: AAA40819.1
      X16003 mRNA Translation: CAA34134.1
      M74449 mRNA Translation: AAA19867.1
      RefSeqiNP_037102.1, NM_012970.3
      XP_006233194.1, XM_006233132.3
      XP_006233195.1, XM_006233133.3
      XP_006233196.1, XM_006233134.3
      XP_006233197.1, XM_006233135.3
      XP_008759593.1, XM_008761371.2

      Genome annotation databases

      EnsembliENSRNOT00000050149; ENSRNOP00000042653; ENSRNOG00000018285
      ENSRNOT00000092365; ENSRNOP00000075841; ENSRNOG00000018285
      ENSRNOT00000092450; ENSRNOP00000075852; ENSRNOG00000018285

      Entry informationi

      Entry nameiKCNA2_RAT
      AccessioniPrimary (citable) accession number: P63142
      Secondary accession number(s): P15386, Q02010
      Entry historyiIntegrated into UniProtKB/Swiss-Prot: September 13, 2004
      Last sequence update: September 13, 2004
      Last modified: September 12, 2018
      This is version 140 of the entry and version 1 of the sequence. See complete history.
      Entry statusiReviewed (UniProtKB/Swiss-Prot)
      Annotation programChordata Protein Annotation Program


      Keywords - Technical termi

      3D-structure, Complete proteome, Reference proteome
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      Main funding by: National Institutes of Health

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