Potassium voltage-gated channel subfamily D member 2 - Q9NZV8 (KCND2_HUMAN)

 

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Function
Voltage-gated potassium channel that mediates transmembrane potassium transport in excitable membranes, primarily in the brain. Mediates the major part of the dendritic A-type current I(SA) in brain neurons (By similarity). This current is activated at membrane potentials that are below the threshold for action potentials. It regulates neuronal excitability, prolongs the latency before the first spike in a series of action potentials, regulates the frequency of repetitive action potential firing, shortens the duration of action potentials and regulates the back-propagation of action potentials from the neuronal cell body to the dendrites. Contributes to the regulation of the circadian rhythm of action potential firing in suprachiasmatic nucleus neurons, which regulates the circadian rhythm of locomotor activity (By similarity). Functions downstream of the metabotropic glutamate receptor GRM5 and plays a role in neuronal excitability and in nociception mediated by activation of GRM5 (By similarity). Mediates the transient outward current I(to) in rodent heart left ventricle apex cells, but not in human heart, where this current is mediated by another family member. Forms tetrameric potassium-selective channels through which potassium ions pass in accordance with their electrochemical gradient (PubMed:10551270, PubMed:15454437, PubMed:14695263, PubMed:14623880, PubMed:14980201, PubMed:16934482, PubMed:24811166, PubMed:24501278). The channel alternates between opened and closed conformations in response to the voltage difference across the membrane (PubMed:11507158). Can form functional homotetrameric channels and heterotetrameric channels that contain variable proportions of KCND2 and KCND3; channel properties depend on the type of pore-forming alpha subunits that are part of the channel. In vivo, membranes probably contain a mixture of heteromeric potassium channel complexes. Interaction with specific isoforms of the regulatory subunits KCNIP1, KCNIP2, KCNIP3 or KCNIP4 strongly increases expression at the cell surface and thereby increases channel activity; it modulates the kinetics of channel activation and inactivation, shifts the threshold for channel activation to more negative voltage values, shifts the threshold for inactivation to less negative voltages and accelerates recovery after inactivation (PubMed:15454437, PubMed:14623880, PubMed:14980201, PubMed:19171772, PubMed:24501278, PubMed:24811166). Likewise, interaction with DPP6 or DPP10 promotes expression at the cell membrane and regulates both channel characteristics and activity (By similarity). UniProt
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Subunit Structure
Homotetramer or heterotetramer with KCND1 or KCND3 (PubMed:14980201, PubMed:16934482, PubMed:24811166). Associates with the regulatory subunits KCNIP1, KCNIP2, KCNIP3 and KCNIP4 (PubMed:10676964, PubMed:11287421, PubMed:11847232, PubMed:12451113, PubMed:15358149, PubMed:14623880, PubMed:14980201, PubMed:14980207, PubMed:24811166). In vivo, probably exists as heteromeric complex containing variable proportions of KCND1, KCND2, KCND3, KCNIP1, KCNIP2, KCNIP3, KCNIP4, DPP6 and DPP10 (PubMed:19171772). The tetrameric channel can associate with up to four regulatory subunits, such as KCNIP2 or KCNIP4 (PubMed:14623880, PubMed:14980201, PubMed:24811166). Interaction with four KCNIP4 chains does not reduce interaction with DPP10 (PubMed:24811166). Interacts with DLG4 and NCS1/FREQ (By similarity). Interacts with DLG1 (PubMed:19213956). Probably part of a complex consisting of KCNIP1, KCNIP2 isoform 3 and KCND2 (PubMed:15358149). Interacts with FLNA, FLNC, DPP6 and DPP10 (PubMed:11102480, PubMed:15454437, PubMed:24811166). UniProt
Domain
The C-terminal cytoplasmic region is important for normal expression at the cell membrane and modulates the voltage-dependence of channel activation and inactivation (PubMed:16934482). It is required for interaction with KCNIP2, and probably other family members as well (By similarity). UniProt
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Data in green originates from UniProtKB  
Variation data (sourced from UniProt) shows non-genetic variation from the ExPASy   and dbSNP   websites.
Data in yellow originates from Pfam  , by interacting with the HMMER3 web site  
Data in purple originates from Phosphosite  .
Data in orange originates from the SCOP   (version 1.75) and SCOPe   (version 2.04) classifications.
Data in grey has been calculated using BioJava  . Protein disorder predictions are based on JRONN (Troshin, P. and Barton, G. J. unpublished), a Java implementation of RONN  
  • Red: potentially disorderd region
  • Blue: probably ordered region.
Hydropathy has been calculated using a sliding window of 15 residues and summing up scores from standard hydrophobicity tables.
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  • Blue: hydrophilic.
Data in lilac represent the genomic exon structure projected onto the UniProt sequence.
Data in blue originates from PDB
  • Secstruc: Secondary structure projected from representative PDB entries onto the UniProt sequence.
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The PDB to UniProt mapping is based on the data provided by the EBI SIFTS project. See also Velankar et al., Nucleic Acids Research 33, D262-265 (2005).
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