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Quantitative modeling of currents from a voltage gated ion channel undergoing fast inactivation

Camacho, CJ (2008) Quantitative modeling of currents from a voltage gated ion channel undergoing fast inactivation. PLoS ONE, 3 (10).

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Ion channels play a central role in setting gradients of ion concentration and electrostatic potentials, which in turn regulate sensory systems and other functions. Based on the structure of the open configuration of the Kv1.2 channel and the suggestion that the two ends of the N-terminal inactivating peptide form a bivalent complex that simultaneously blocks the channel pore and binds to the cytoplasmic T1 domain, we propose a six state kinetic model that for the first time reproduces the kinetics of recovery of the Drosophila Shaker over the full range of time scales and hyperpolarization potentials, including tail currents. The model is motivated by a normal mode analysis of the inactivated channel that suggests that a displacement consistent with models of the closed state propagates to the T1 domain via the S1-T1 linker. This motion stretches the bound (inactivating) peptide, hastening the unblocking of the pore. This pulling force is incorporated into the rates of the open to blocked states, capturing the fast recovery phase of the current for repolarization events shorter than 1 ms. If the membrane potential is hyperpolarized, essential dynamics further suggests that the T1 domain returns to a configuration where the peptide is unstretched and the S1-T1 linker is extended. Coupling this novel hyperpolarized substate to the closed, open and blocked pore states is enough to quantitatively estimate the number of open channels as a function of time and membrane potential. A straightforward prediction of the model is that a slow ramping of the potential leads to very small currents. © 2008 Camacho.


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Item Type: Article
Status: Published
CreatorsEmailPitt UsernameORCID
Camacho, CJccamacho@pitt.eduCCAMACHO
ContributionContributors NameEmailPitt UsernameORCID
Date: 3 October 2008
Date Type: Publication
Journal or Publication Title: PLoS ONE
Volume: 3
Number: 10
DOI or Unique Handle: 10.1371/journal.pone.0003342
Schools and Programs: School of Medicine > Computational Biology
Refereed: Yes
PubMed Central ID: PMC2551740
PubMed ID: 18833322
Date Deposited: 24 Jul 2012 18:47
Last Modified: 15 Oct 2017 04:55


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