Potassium voltage-gated channel subfamily A member 4

Definition:

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. 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. Likewise, a heterotetrameric channel formed by KCNA1 and KCNA4 shows rapid inactivation.

References:

[1]. M Ramaswami, et al. Human potassium channel genes: Molecular cloning and functional expression. Mol Cell Neurosci. 1990 Dec;1(3):214-23. [Content Brief]

[2]. S Po, et al. Heteromultimeric assembly of human potassium channels. Molecular basis of a transient outward current?. Circ Res. 1993 Jun;72(6):1326-36. [Content Brief]

[3]. Namik Kaya, et al. KCNA4 deficiency leads to a syndrome of abnormal striatum, congenital cataract and intellectual disability. J Med Genet. 2016 Nov;53(11):786-792. [Content Brief]

[4]. Paola Imbrici, et al. Episodic ataxia type 1 mutations in the KCNA1 gene impair the fast inactivation properties of the human potassium channels Kv1.4-1.1/Kvbeta1.1 and Kv1.4-1.1/Kvbeta1.2. Eur J Neurosci. 2006 Dec;24(11):3073-83. [Content Brief]

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