Neurochemical Research

, Volume 33, Issue 10, pp 2078–2084 | Cite as

Enhanced Trafficking of Tetrameric Kv4.3 Channels by KChIP1 Clamping

Original Paper


The cytoplamsic auxiliary KChIPs modulate surface expression and gating properties of Kv4 channels. Recent co-crystal structure of Kv4.3 N-terminus and KChIP1 reveals a clamping action of the complex in which a single KChIP1 molecule laterally binds two neighboring Kv4.3 N-termini at different locations, thus forming two contact interfaces involved in the protein–protein interaction. In the second interface, it functions to stabilize the tetrameric assembly, but the role it plays in channel trafficking remains elusive. In this study, we examined the effects of KChIP1 on Kv4 protein trafficking in COS-7 cells expressing EGFP-tagged Kv4.3 channels using confocal microscopy. Mutations either in KChIP1 (KChIP1 L39E-Y57A-K61A) or Kv4.3 (Kv4.3 E70A-F73E) that disrupt the protein–protein interaction within the second interface can reduce surface expression of Kv4 channel proteins. Kv4.3 C110A, the Zn2+ binding site mutation in T1 domain, that disrupts the tetrameric assembly of the channels can be rescued by WT KChIP1, but not the KChIP1 triple mutant. These results were further confirmed by whole cell current recordings in oocytes. Our findings show that key residues of second interface involved in stabilizing tetrameric assembly can regulate the channel trafficking, indicating an intrinsic link between tetrameric assembly and channel trafficking. The results also suggest that formation of octameric Kv4 and KChIP complex by KChIPs clamping takes place before their trafficking to final destination on the cell surface.


KChIP1 Kv4.3 T1 zinc binding site Trafficking Tetrameric assembly 



We thank Yanhua Huang and Yanxin Lu for their technical assistance for this work and Hao Chen for helpful discussion on the manuscript. The preparation of this manuscript was supported by research grants from the National Science Foundation of China, 30630017 and the Ministry of Science Technology of China, 2006AA02Z183 and 2007CB512100 to KWW.


  1. 1.
    Abbott GW, Goldstein SA (1998) A superfamily of small potassium channel subunits: form and function of the MinK-related peptides (MiRPs). Q Rev Biophys 31(4):357–398PubMedCrossRefGoogle Scholar
  2. 2.
    Shibata R et al (2003) A fundamental role for KChIPs in determining the molecular properties and trafficking of Kv4.2 potassium channels. J Biol Chem 278(38):36445–36454PubMedCrossRefGoogle Scholar
  3. 3.
    Rhodes KJ et al (2004) KChIPs and Kv4 alpha subunits as integral components of A-type potassium channels in mammalian brain. J Neurosci 24(36):7903–7915PubMedCrossRefGoogle Scholar
  4. 4.
    An WF et al (2000) Modulation of A-type potassium channels by a family of calcium sensors. Nature 403(6769):553–556PubMedCrossRefGoogle Scholar
  5. 5.
    Kuo HC et al (2001) A defect in the Kv channel-interacting protein 2 (KChIP2) gene leads to a complete loss of I(to) and confers susceptibility to ventricular tachycardia. Cell 107(6):801–813PubMedCrossRefGoogle Scholar
  6. 6.
    Nadal MS et al (2001) Evidence for the presence of a novel Kv4-mediated A-type K(+) channel-modifying factor. J Physiol 537(Pt 3):801–809PubMedCrossRefGoogle Scholar
  7. 7.
    Holmqvist MH et al (2002) Elimination of fast inactivation in Kv4 A-type potassium channels by an auxiliary subunit domain. Proc Natl Acad Sci USA 99(2):1035–1040PubMedCrossRefGoogle Scholar
  8. 8.
    Jahng AW et al (2002) Zinc mediates assembly of the T1 domain of the voltage-gated K channel 4.2. J Biol Chem 277(49):47885–47890PubMedCrossRefGoogle Scholar
  9. 9.
    Scannevin RH et al (2004) Two N-terminal domains of Kv4 K(+) channels regulate binding to and modulation by KChIP1. Neuron 41(4):587–598PubMedCrossRefGoogle Scholar
  10. 10.
    Li M, Jan YN, Jan LY (1992) Specification of subunit assembly by the hydrophilic amino-terminal domain of the Shaker potassium channel. Science 257(5074):1225–1230PubMedCrossRefGoogle Scholar
  11. 11.
    Kunjilwar K et al (2004) KChIP3 rescues the functional expression of Shal channel tetramerization mutants. J Biol Chem 279(52):54542–54551PubMedCrossRefGoogle Scholar
  12. 12.
    Wang H et al (2007) Structural basis for modulation of Kv4 K+ channels by auxiliary KChIP subunits. Nat Neurosci 10(1):32–39PubMedCrossRefGoogle Scholar
  13. 13.
    Pioletti M et al (2006) Three-dimensional structure of the KChIP1-Kv4.3 T1 complex reveals a cross-shaped octamer. Nat Struct Mol Biol 13(11):987–995PubMedCrossRefGoogle Scholar
  14. 14.
    Kim LA et al (2004) Three-dimensional structure of I(to); Kv4.2-KChIP2 ion channels by electron microscopy at 21 Angstrom resolution. Neuron 41(4):513–519PubMedCrossRefGoogle Scholar
  15. 15.
    Jow F et al (2004) Functional coupling of intracellular calcium and inactivation of voltage-gated Kv1.1/Kvbeta1.1 A-type K+ channels. Proc Natl Acad Sci USA 101(43):15535–15540PubMedCrossRefGoogle Scholar
  16. 16.
    Beck EJ et al (2002) Remodelling inactivation gating of Kv4 channels by KChIP1, a small-molecular-weight calcium-binding protein. J Physiol 538(Pt 3):691–706PubMedCrossRefGoogle Scholar
  17. 17.
    Wang G et al (2005) Functionally active t1-t1 interfaces revealed by the accessibility of intracellular thiolate groups in kv4 channels. J Gen Physiol 126(1):55–69PubMedCrossRefGoogle Scholar
  18. 18.
    Long SB, Campbell EB, Mackinnon R (2005) Crystal structure of a mammalian voltage-dependent Shaker family K+ channel. Science 309(5736):897–903PubMedCrossRefGoogle Scholar
  19. 19.
    Wang G, Covarrubias M (2006) Voltage-dependent gating rearrangements in the intracellular T1–T1 interface of a K+ channel. J Gen Physiol 127(4):391–400PubMedCrossRefGoogle Scholar
  20. 20.
    Callsen B et al (2005) Contribution of N- and C-terminal channel domains to Kv channel interacting proteins in a mammalian cell line. J Physiol 568(Pt 2):397–412PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  1. 1.Neuroscience Research Institute and Department of Neurobiology, Key Laboratory for Neuroscience of the Ministry of EducationCenter for Protein Sciences, Peking University Health Science CenterBeijingChina

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