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Details on Person UniProt:O15554 KCNN4

Class:IdReferenceGeneProduct:57943
_chainChangeLogchain:1-427 added on Fri February 6 2015
_displayNameUniProt:O15554 KCNN4
_timestamp2026-02-20 22:22:55
chainchain:1-427
checksum23F9AF66609B410F
commentFUNCTION Intermediate conductance calcium-activated potassium channel that mediates the voltage-independent transmembrane transfer of potassium across the cell membrane through a constitutive interaction with calmodulin which binds the intracellular calcium allowing its opening (PubMed:10026195, PubMed:10961988, PubMed:11425865, PubMed:15831468, PubMed:17157250, PubMed:18796614, PubMed:26148990, PubMed:9326665, PubMed:9380751, PubMed:9407042). The current is characterized by a voltage-independent activation, an intracellular calcium concentration increase-dependent activation and a single-channel conductance of about 25 picosiemens (PubMed:9326665, PubMed:9380751, PubMed:9407042). Also presents an inwardly rectifying current, thus reducing its already small outward conductance of potassium ions, which is particularly the case when the membrane potential displays positive values, above + 20 mV (PubMed:9326665, PubMed:9380751, PubMed:9407042). Controls calcium influx during vascular contractility by being responsible of membrane hyperpolarization induced by vasoactive factors in proliferative vascular smooth muscle cell types (By similarity). Following calcium influx, the consecutive activation of KCNN4 channel leads to a hyperpolarization of the cell membrane potential and hence an increase of the electrical driving force for further calcium influx promoting sustained calcium entry in response to stimulation with chemotactic peptides (PubMed:26418693). Required for maximal calcium influx and proliferation during the reactivation of naive T-cells (PubMed:17157250, PubMed:18796614). Plays a role in the late stages of EGF-induced macropinocytosis through activation by PI(3)P (PubMed:24591580).CATALYTIC ACTIVITY K(+)(in) = K(+)(out)ACTIVITY REGULATION The channel is inhibited by clotrimazole and charybdotoxin but is insensitive to apamin.SUBUNIT Homodimer (PubMed:29953543). Homotetramer (PubMed:29724949). Heterotetramer of potassium channel proteins (Probable). Interacts with MTMR6; this interaction leads to selective dephosphorylation of PI(3)P in a lipid microdomain adjacent to KCNN4, resulting in a decrease of intermediate conductance calcium-activated potassium channel activity (PubMed:15831468). Interacts (via the C-tail domain) with CALM1; the calmodulin binding is constitutive, does not require calcium and mediates calcium-dependent gating and four calmodulin molecules bind to one channel tetramer (PubMed:10026195).INTERACTION Targeted to membrane ruffles after EGF stimulation.TISSUE SPECIFICITY Widely expressed in non-excitable tissues.INDUCTION Up-regulated by phorbol myristate acetate (PMA) and phytohemagglutinin (PHA) in T-cells.DOMAIN Transmembrane helices S5 and S6 form the ion channel pore, which is surrounded bymembrane embedded helices S1 to S4 (PubMed:29724949). The S4-S5 linker, which contains two distinct helices, undergoes conformational changes upon calmodulin binding to open the channel pore (PubMed:29724949).PTM Phosphorylation at His-358 by NDKB activates the intermediate conductance calcium-activated potassium channel activity, and conversely its dephosphorylation by PHPT1 inhibits this activity.DISEASE The disease is caused by variants affecting the gene represented in this entry.SIMILARITY Belongs to the potassium channel KCNN family. KCa3.1/KCNN4 subfamily.
descriptionrecommendedName: fullName evidence="24"Intermediate conductance calcium-activated potassium channel protein 4 shortName: SKCa 4 shortName: SKCa4 shortName evidence="22"hSK4 alternativeName: fullName evidence="19"Gardos channel alternativeName: IKCa1 shortName evidence="21"hIK1 alternativeName: fullName evidence="20"KCa3.1 alternativeName: Putative Gardos channel alternativeName: fullName evidence="23"hKCa4
geneNameKCNN4
IK1
IKCA1
KCA4
SK4
identifierO15554
isSequenceChangedFALSE
keyword3D-structure
Calmodulin-binding
Cell membrane
Cell projection
Disease variant
Hereditary hemolytic anemia
Immunity
Ion channel
Ion transport
Membrane
Phosphoprotein
Proteomics identification
Reference proteome
Transmembrane
Transmembrane helix
Transport
modified[InstanceEdit:9836292] Weiser, Joel, 2023-05-25
[InstanceEdit:9852000] Weiser, Joel, 2023-11-03
[InstanceEdit:9926675] Weiser, Joel, 2024-11-03
[InstanceEdit:9983091] Weiser, Joel, 2026-02-20
nameKCNN4
referenceDatabase[ReferenceDatabase:2] UniProt
referenceGene[ReferenceDNASequence:8989020] ENSEMBL:ENSG00000104783 KCNN4 [Homo sapiens]
secondaryIdentifierKCNN4_HUMAN
Q53XR4
sequenceLength427
species[Species:48887] Homo sapiens
(referenceEntity)[EntityWithAccessionedSequence:977543] KCNN4 [plasma membrane] [Homo sapiens]
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