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Kinetic models of a K channel with 2 stage voltage sensor activation and an opening step

  • S. R. Vaccaro
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Abstract

The activation of a K channel with 2 voltage sensors and a separate opening step may be described by a 4 state kinetic equation. If ko and kc are the opening and closing rates, and α and β are the voltage sensor rates such that ko ≫α,kc≫β and ko ≫ kc, the kinetic equation may be reduced to a 3 state model where the effective backward rate from the activated-open state is 2βkc/(ko+kc). However, if a K channel voltage sensor activates in 2 stages, and there is a separate opening step, the occupation probabilities of the states of the channel satisfy a 10 state kinetic equation. When the time constants of the characteristic equation for each voltage sensor differ by an order of magnitude, and ko ≫ kc, the open state probability is proportional to n2, where n satisfies a rate equation, and the derived rates have a similar voltage dependence to the rates αn and βn from voltage clamp data.

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Cite

BibTeXRIS
BibTeX
@misc{vaccaro2026kinetic,
  title = {{Kinetic models of a K channel with 2 stage voltage sensor activation and an opening step}},
  author = {S. R. Vaccaro},
  howpublished = {arXiv},
  year = {2026},
  month = nov,
  doi = {10.48550/arxiv.2611.08354},
  eprint = {2611.08354},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2611.08354},
}
RIS
TY  - UNPB
TI  - Kinetic models of a K channel with 2 stage voltage sensor activation and an opening step
AU  - S. R. Vaccaro
PY  - 2026
DA  - 2026/11/05
PB  - arXiv
DO  - 10.48550/arxiv.2611.08354
UR  - https://arxiv.org/abs/2611.08354
AB  - The activation of a K channel with 2 voltage sensors and a separate opening step may be described by a 4 state kinetic equation. If k_o and k_c are the opening and closing rates, and α and β are the voltage sensor rates such that k_o ≫α,k_c≫β and k_o ≫ k_c, the kinetic equation may be reduced to a 3 state model where the effective backward rate from the activated-open state is 2βk_c/(k_o+k_c). However, if a K channel voltage sensor activates in 2 stages, and there is a separate opening step, the occupation probabilities of the states of the channel satisfy a 10 state kinetic equation. When the time constants of the characteristic equation for each voltage sensor differ by an order of magnitude, and k_o ≫ k_c, the open state probability is proportional to n^2, where n satisfies a rate equation, and the derived rates have a similar voltage dependence to the rates α_n and β_n from voltage clamp data.
ER  -