KCNA4
Description
The KCNA4 (potassium voltage-gated channel subfamily A member 4) is a protein-coding gene located on chromosome 11.
KCNA4, also known as Kv1.4, is a protein encoded by the KCNA4 gene in humans. It plays a crucial role in the cardiac transient outward potassium current (Ito1), a key component in the repolarization phase 1 of the cardiac action potential. Potassium channels, including KCNA4, are a diverse and complex class of voltage-gated ion channels with various functions, including regulating neurotransmitter release, heart rate, insulin secretion, neuronal excitability, epithelial electrolyte transport, smooth muscle contraction, and cell volume. KCNA4 belongs to the shaker-related subfamily of potassium channels, characterized by six membrane-spanning domains with a shaker-type repeat in the fourth segment. It contributes to the A-type potassium current, which is important for the fast repolarizing phase of action potentials in the heart. The KCNA4 gene is intronless and is located on chromosome 1, clustered with genes KCNA3 and KCNA10. KCNA4 contains a tandem inactivation domain at its N-terminus.
KCNA4 (Kv1.4) is a voltage-gated potassium channel that facilitates potassium ion movement across excitable membranes. It assembles into tetrameric structures, forming potassium-selective channels that allow potassium ions to pass based on their electrochemical gradient. The channel transitions between open and closed states in response to changes in membrane potential (PubMed:19912772, PubMed:8495559). KCNA4 can create both homotetrameric channels, composed solely of KCNA4 subunits, and heterotetrameric channels that incorporate varying proportions of KCNA1, KCNA2, KCNA4, KCNA5, and potentially other family members. The specific composition of alpha subunits within the channel dictates its functional properties (PubMed:8495559). Cytoplasmic beta subunits further modulate channel behavior by influencing the subcellular localization of alpha subunits and promoting rapid inactivation. In living organisms, membranes likely contain a mix of heteromeric potassium channel complexes, making it challenging to pinpoint the specific potassium channel family member responsible for observed currents in intact tissues. Homotetrameric KCNA4 channels open in response to membrane depolarization, followed by swift spontaneous closure (PubMed:19912772, PubMed:8495559). Similarly, a heterotetrameric channel formed by KCNA1 and KCNA4 exhibits rapid inactivation (PubMed:17156368). {ECO:0000269|PubMed:17156368, ECO:0000269|PubMed:19912772, ECO:0000269|PubMed:27582084, ECO:0000269|PubMed:8495559}
KCNA4 is also known as HBK4, HK1, HPCN2, HUKII, KCNA4L, KCNA8, KV1.4, MCIDDS, PCN2.
