KCNA5

Potassium channels represent the most complex class of voltage-gated ino channels from both functional and structural standpoints. Their diverse functions include regulating neurotransmitter release, heart rate, insulin secretion, neuronal excitability, epithelial electrolyte transport, smooth muscle contraction, and cell volume. Four sequence-related potassium channel genes - shaker, shaw, shab, and shal - have been identified in Drosophila, and each has been shown to have human homolog(s). This gene encodes a member of the potassium channel, voltage-gated, shaker-related subfamily. This member contains six membrane-spanning domains with a shaker-type repeat in the fourth segment. It belongs to the delayed rectifier class, the function of which could restore the resting membrane potential of beta cells after depolarization and thereby contribute to the regulation of insulin secretion. This gene is intronless, and the gene is clustered with genes KCNA1 and KCNA6 on chromosome 12. Defects in this gene are a cause of familial atrial fibrillation type 7 (ATFB7).

Full Name

potassium voltage-gated channel subfamily A member 5

Function

Voltage-gated potassium channel that mediates transmembrane potassium transport in excitable membranes. 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. Can form functional homotetrameric channels and heterotetrameric channels that contain variable proportions of KCNA1, KCNA2, KCNA4, KCNA5, and possibly other family members as well; channel properties depend on the type of alpha subunits that are part of the channel (PubMed:12130714).
Channel properties are modulated by cytoplasmic beta subunits that regulate the subcellular location of the alpha subunits and promote rapid inactivation (PubMed:12130714).
Homotetrameric channels display rapid activation and slow inactivation (PubMed:8505626, PubMed:12130714).
May play a role in regulating the secretion of insulin in normal pancreatic islets. Isoform 2 exhibits a voltage-dependent recovery from inactivation and an excessive cumulative inactivation (PubMed:11524461).

Biological Process

Atrial cardiac muscle cell action potentialManual Assertion Based On ExperimentIMP:BHF-UCL
Membrane hyperpolarizationManual Assertion Based On ExperimentIMP:BHF-UCL
Membrane repolarization during atrial cardiac muscle cell action potentialManual Assertion Based On ExperimentIMP:BHF-UCL
Membrane repolarization during bundle of His cell action potentialManual Assertion Based On ExperimentIMP:BHF-UCL
Membrane repolarization during SA node cell action potentialManual Assertion Based On ExperimentIMP:BHF-UCL
Negative regulation of cytosolic calcium ion concentrationIEA:Ensembl
Notch signaling pathwayIEA:Ensembl
Positive regulation of G1/S transition of mitotic cell cycleIEA:Ensembl
Positive regulation of myoblast proliferationIEA:Ensembl
Potassium ion export across plasma membraneManual Assertion Based On ExperimentIDA:BHF-UCL
Potassium ion homeostasisIEA:Ensembl
Potassium ion transmembrane transportManual Assertion Based On ExperimentIDA:UniProtKB
Potassium ion transportManual Assertion Based On ExperimentIDA:MGI
Protein homooligomerizationIEA:InterPro
Regulation of atrial cardiac muscle cell membrane repolarizationManual Assertion Based On ExperimentIMP:BHF-UCL
Regulation of heart rate by cardiac conductionManual Assertion Based On ExperimentIMP:BHF-UCL
Regulation of insulin secretionManual Assertion Based On ExperimentTAS:BHF-UCL
Regulation of membrane potentialManual Assertion Based On ExperimentIDA:BHF-UCL
Regulation of potassium ion transportManual Assertion Based On ExperimentIMP:BHF-UCL
Regulation of vasoconstrictionIEA:Ensembl
Response to hydrogen peroxideIEA:Ensembl
Response to hyperoxiaIEA:Ensembl
Response to hypoxiaIEA:Ensembl
Response to mechanical stimulusIEA:Ensembl
Response to organic substanceIEA:Ensembl

Cellular Location

Cell membrane

Involvement in disease

Atrial fibrillation, familial, 7 (ATFB7):
A familial form of atrial fibrillation, a common sustained cardiac rhythm disturbance. Atrial fibrillation is characterized by disorganized atrial electrical activity and ineffective atrial contraction promoting blood stasis in the atria and reduces ventricular filling. It can result in palpitations, syncope, thromboembolic stroke, and congestive heart failure.

Topology

Cytoplasmic: 1-247
Helical: 248-269
Extracellular: 270-323
Helical: 324-345
Cytoplasmic: 346-356
Helical: 357-377
Extracellular: 378-395
Helical: 396-416
Cytoplasmic: 417-431
Helical: 432-453
Extracellular: 454-467
Helical: 468-487
Extracellular: 488-494
Helical: 495-523
Cytoplasmic: 524-613

PTM

Sumoylated on Lys-221, and Lys-536, preferentially with SUMO3. Sumoylation regulates the voltage sensitivity of the channel.