Potassium voltage-gated channel subfamily A member 2 - P63142 (KCNA2_RAT)

 

Protein Feature View of PDB entries mapped to a UniProtKB sequence  

  • Number of PDB entries for P63142: 10
 
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 cardiovascular system. Prevents aberrant action potential firing and regulates neuronal output. 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:12151401, PubMed:21602278, PubMed:24472174). 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:8495559, PubMed:15618540, PubMed:20805574, PubMed:23725331). 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:18003609, PubMed:19713757). In vivo, membranes probably contain a mixture of heteromeric potassium channel complexes, making it difficult to assign currents observed in intact tissues to a particular potassium channel family member. Homotetrameric KCNA2 forms a delayed-rectifier potassium channel that opens in response to membrane depolarization, followed by slow spontaneous channel closure (PubMed:1715584, PubMed:16770729, PubMed:17766348, PubMed:18003609, PubMed:18638484, PubMed:19713757, PubMed:20089912). In contrast, a heteromultimer formed by KCNA2 and KCNA4 shows rapid inactivation (PubMed:8495559). 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 (PubMed:23318870). KCNA2-containing channels play a presynaptic role and prevent hyperexcitability and aberrant action potential firing (PubMed:12777451). Response to toxins that are selective for KCNA2-containing potassium channels suggests that in Purkinje cells, dendritic subthreshold KCNA2-containing potassium channels prevent random spontaneous calcium spikes, suppressing dendritic hyperexcitability without hindering the generation of somatic action potentials, and thereby play an important role in motor coordination (PubMed:16210348). Plays a role in the induction of long-term potentiation of neuron excitability in the CA3 layer of the hippocampus (By similarity). May function as down-stream effector for G protein-coupled receptors and inhibit GABAergic inputs to basolateral amygdala neurons (PubMed:16306173). May contribute to the regulation of neurotransmitter release, such as gamma-aminobutyric acid (GABA) (PubMed:17869444). Contributes to the regulation of the axonal release of the neurotransmitter dopamine (PubMed:21647367). Reduced KCNA2 expression plays a role in the perception of neuropathic pain after peripheral nerve injury, but not acute pain (PubMed:24472174). Plays a role in the regulation of the time spent in non-rapid eye movement (NREM) sleep. UniProt
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Subunit Structure
Homotetramer and heterotetramer with other channel-forming alpha subunits, such as KCNA1, KCNA4, KCNA5, KCNA6 and KCNA7 (PubMed:8495559, PubMed:8361540, PubMed:10896669, PubMed:12777451, PubMed:12632190, PubMed:15618540, PubMed:11007484, PubMed:16002581, PubMed:18004376, PubMed:20534430). Channel activity is regulated by interaction with beta subunits, including KCNAB1 and KCNAB2 (PubMed:18003609, PubMed:19713757, PubMed:16002581, PubMed:18004376, PubMed:20534430, PubMed:20360102, PubMed:23705070). Identified in a complex with KCNA1 and KCNAB2 (PubMed:11086297, PubMed:23318870). Identified in a complex with KCNA5 and KCNAB1 (By similarity). Identified in a complex with KCNA4 and FYN (By similarity). Interacts (via C-terminus) with the PDZ domains of DLG1 and DLG2 (PubMed:7477295). Interacts with DLG4 (via PDZ domain) (PubMed:7477295, PubMed:20089912). Interacts with PTK2B (PubMed:11739373). Interacts (via C-terminus) with CTTN (PubMed:12151401). Interacts (via N-terminal cytoplasmic domain) with RHOA (GTP-bound form); this regulates channel activity by reducing location at the cell surface in response to CHRM1 activation (PubMed:9635436). Interacts with DRD2 (By similarity). Interacts with SIGMAR1; cocaine consumption leads to increased interaction (By similarity). Interacts with CNTNAP2 (PubMed:10624965). Interacts with ADAM22 (PubMed:20089912). UniProt
Domain
The transmembrane segment S4 functions as voltage-sensor and is characterized by a series of positively charged amino acids at every third position. Channel opening and closing is effected by a conformation change that affects the position and orientation of the voltage-sensor paddle formed by S3 and S4 within the membrane. A transmembrane electric field that is positive inside would push the positively charged S4 segment outwards, thereby opening the pore, while a field that is negative inside would pull the S4 segment inwards and close the pore. Changes in the position and orientation of S4 are then transmitted to the activation gate formed by the inner helix bundle via the S4-S5 linker region. UniProt
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