Recombinant Human Potassium voltage-gated channel subfamily A member 1 (KCNA1), partial

Function

Voltage-gated potassium channel that mediates transmembrane potassium transport in excitable membranes, primarily in the brain and the central nervous system, but also in the kidney (PubMed:19903818, PubMed:8845167). Contributes to the regulation of the membrane potential and nerve signaling, and prevents neuronal hyperexcitability (PubMed:17156368). 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). Can form functional homotetrameric channels and heterotetrameric channels that contain variable proportions of KCNA1, KCNA2, KCNA4, KCNA5, KCNA6, KCNA7, and possibly other family members as well; channel properties depend on the type of alpha subunits that are part of the channel (PubMed:12077175, PubMed:17156368). Channel properties are modulated by cytoplasmic beta subunits that regulate the subcellular location of the alpha subunits and promote rapid inactivation of delayed rectifier potassium channels (PubMed:12077175, PubMed:17156368). 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 KCNA1 forms a delayed-rectifier potassium channel that opens in response to membrane depolarization, followed by slow spontaneous channel closure (PubMed:19307729, PubMed:19903818, PubMed:19912772, PubMed:19968958). In contrast, a heterotetrameric channel formed by KCNA1 and KCNA4 shows rapid inactivation (PubMed:17156368). Regulates neuronal excitability in hippocampus, especially in mossy fibers and medial perforant path axons, preventing neuronal hyperexcitability. Response to toxins that are selective for KCNA1, respectively for KCNA2, suggests that heteromeric potassium channels composed of both KCNA1 and KCNA2 play a role in pacemaking and regulate the output of deep cerebellar nuclear neurons (By similarity). May function as down-stream effector for G protein-coupled receptors and inhibit GABAergic inputs to basolateral amygdala neurons (By similarity). May contribute to the regulation of neurotransmitter release, such as gamma-aminobutyric acid (GABA) release (By similarity). Plays a role in regulating the generation of action potentials and preventing hyperexcitability in myelinated axons of the vagus nerve, and thereby contributes to the regulation of heart contraction (By similarity). Required for normal neuromuscular responses (PubMed:11026449, PubMed:17136396). Regulates the frequency of neuronal action potential firing in response to mechanical stimuli, and plays a role in the perception of pain caused by mechanical stimuli, but does not play a role in the perception of pain due to heat stimuli (By similarity). Required for normal responses to auditory stimuli and precise location of sound sources, but not for sound perception (By similarity). The use of toxins that block specific channels suggest that it contributes to the regulation of the axonal release of the neurotransmitter dopamine (By similarity). Required for normal postnatal brain development and normal proliferation of neuronal precursor cells in the brain (By similarity). Plays a role in the reabsorption of Mg(2+) in the distal convoluted tubules in the kidney and in magnesium ion homeostasis, probably via its effect on the membrane potential (PubMed:19307729, PubMed:23903368)

Subcellular Location

Cell membrane (Multi-pass membrane protein); Membrane; Cell projection, axon; Cytoplasmic vesicle; Perikaryon; Endoplasmic reticulum; Cell projection, dendrite; Cell junction; Synapse; Presynaptic cell membrane; Presynapse

Disease Association

Episodic ataxia 1 (EA1) : An autosomal dominant disorder characterized by brief episodes of ataxia and dysarthria. Neurological examination during and between the attacks demonstrates spontaneous, repetitive discharges in the distal musculature (myokymia) that arise from peripheral nerve. Nystagmus is absent. [The disease is caused by variants affecting the gene represented in this entry] | Myokymia isolated 1 (MK1) : A condition characterized by spontaneous involuntary contraction of muscle fiber groups that can be observed as vermiform movement of the overlying skin. Electromyography typically shows continuous motor unit activity with spontaneous oligo- and multiplet-discharges of high intraburst frequency (myokymic discharges). Isolated spontaneous muscle twitches occur in many persons and have no grave significance. [The disease is caused by variants affecting the gene represented in this entry]

Tissue Specificity

Detected adjacent to nodes of Ranvier in juxtaparanodal zones in spinal cord nerve fibers, but also in paranodal regions in some myelinated spinal cord axons (at protein level) (PubMed:11086297). Detected in the islet of Langerhans (PubMed:21483673)

Subunit

Homotetramer and heterotetramer with other channel-forming alpha subunits, such as KCNA2, KCNA4, KCNA5, KCNA6 and KCNA7 (PubMed:12077175, PubMed:17156368). Channel activity is regulated by interaction with the beta subunits KCNAB1 and KCNAB2 (PubMed:12077175, PubMed:17156368). Identified in a complex with KCNA2 and KCNAB2 (PubMed:11086297). Interacts (via C-terminus) with the PDZ domains of DLG1, DLG2 and DLG4 (By similarity). Interacts with LGI1 within a complex containing LGI1, KCNA4 and KCNAB1 (By similarity). Interacts (via N-terminus) with STX1A; this promotes channel inactivation (By similarity). Interacts (via N-terminus) with the heterodimer formed by GNB1 and GNG2; this promotes channel inactivation (By similarity). Can interact simultaneously with STX1A and the heterodimer formed by GNB1 and GNG2 (By similarity). Interacts (via cytoplasmic N-terminal domain) with KCNRG; this inhibits channel activity (PubMed:19968958). Interacts with ANK3; this inhibits channel activity (PubMed:23903368). Interacts with ADAM11 (By similarity)

• Ramaswami M. et al. Human potassium channel genes: molecular cloning and functional expression. — Mol. Cell. Neurosci. (1990)
• Scherer S.E. et al. The finished DNA sequence of human chromosome 12. — Nature (2006)
• Mural R.J. et al. PubMed: CI-5GBD0VIIJ7C63 (SEP-)
• The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). — Genome Res. (2004)
• Freeman S.N. et al. Cloning and characterization of a cDNA encoding a human brain potassium channel. — Biochem. Soc. Trans. (1990)
• Rasband M.N. et al. Subunit composition and novel localization of K+ channels in spinal cord. — J. Comp. Neurol. (2001)
• Hoopengardner B. et al. Nervous system targets of RNA editing identified by comparative genomics. — Science (2003)
• Gubitosi-Klug R.A. et al. The human Kv1.1 channel is palmitoylated, modulating voltage sensing: Identification of a palmitoylation consensus sequence. — Proc. Natl. Acad. Sci. U.S.A. (2005)