KCNA4

Potassium channels represent the most complex class of voltage-gated ion 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 A-type potassium current class, the members of which may be important in the regulation of the fast repolarizing phase of action potentials in heart and thus may influence the duration of cardiac action potential.[provided by RefSeq, Mar 2011]

Potassium Voltage-Gated Channel Subfamily A Member 4

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 (PubMed:19912772, PubMed:8495559).
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:8495559).
Channel properties are modulated by cytoplasmic beta subunits that regulate the subcellular location of the alpha subunits and promote rapid inactivation. In vivo, membranes probably contain a mixture of heteromeric potassium channel complexes, making it difficult to assign currents observed in intact tissues to any particular potassium channel family member. Homotetrameric KCNA4 forms a potassium channel that opens in response to membrane depolarization, followed by rapid spontaneous channel closure (PubMed:19912772, PubMed:8495559).
Likewise, a heterotetrameric channel formed by KCNA1 and KCNA4 shows rapid inactivation (PubMed:17156368).

Potassium ion transmembrane transportManual Assertion Based On ExperimentIDA:UniProtKB
Potassium ion transportManual Assertion Based On ExperimentTAS:ProtInc
Protein homooligomerizationIEA:InterPro
Regulation of ion transmembrane transportIEA:UniProtKB-KW

Cell membrane; Cell projection, axon

Microcephaly, cataracts, impaired intellectual development, and dystonia with abnormal striatum (MCIDDS):
An autosomal recessive syndrome characterized by cognitive impairment, attention deficit hyperactivity disorder, microcephaly, growth retardation, congenital cataract, and dystonia. Brain MRI shows unusual thinning of the lentiform nucleus, predominantly involving the putamen, and swelling in the caudate heads.

Cytoplasmic: 1-304
Helical: 305-326
Extracellular: 327-370
Helical: 371-392
Cytoplasmic: 393-403
Helical: 404-424
Extracellular: 425-439
Helical: 440-460
Cytoplasmic: 461-475
Helical: 476-497
Extracellular: 498-511
Helical: 512-531
Extracellular: 532-538
Helical: 539-567
Cytoplasmic: 568-653