Fast and slow gating are inherent properties of the pore module of the K+ channel Kcv

被引:31
作者
Abenavoli, Alessandra [1 ,2 ]
DiFrancesco, Mattia Lorenzo [1 ,2 ]
Schroeder, Indra [3 ]
Epimashko, Svetlana [1 ,2 ]
Gazzarrini, Sabrina [1 ,2 ]
Hansen, Ulf Peter [3 ]
Thiel, Gerhard [4 ]
Moroni, Anna [1 ,2 ]
机构
[1] Univ Milan, CNR, Dipartimento Biol, I-20133 Milan, Italy
[2] Univ Milan, CNR, Ist Biofis, I-20133 Milan, Italy
[3] Univ Kiel, Dept Biol Struct, D-24098 Kiel, Germany
[4] Tech Univ Darmstadt, Inst Bot, D-64287 Darmstadt, Germany
关键词
MAXIK SELECTIVITY FILTER; PATCH-CLAMP DATA; POTASSIUM-CHANNEL; CHLORELLA VIRUSES; INACTIVATION; INSTABILITY; CHARA; STATE; DISTRIBUTIONS; SPECTROSCOPY;
D O I
10.1085/jgp.200910266
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
Kcv from the chlorella virus PBCV-1 is a viral protein that forms a tetrameric, functional K+ channel in heterologous systems. Kcv can serve as a model system to study and manipulate basic properties of the K+ channel pore because its minimalistic structure (94 amino acids) produces basic features of ion channels, such as selectivity, gating, and sensitivity to blockers. We present a characterization of Kcv properties at the single-channel level. In symmetric 100 mM K+, single-channel conductance is 114 +/- 11 pS. Two different voltage-dependent mechanisms are responsible for the gating of Kcv. "Fast" gating, analyzed by beta distributions, is responsible for the negative slope conductance in the single-channel current-voltage curve at extreme potentials, like in MaxiK potassium channels, and can be explained by depletion-aggravated instability of the filter region. The presence of a "slow" gating is revealed by the very low (in the order of 1-4%) mean open probability that is voltage dependent and underlies the time-dependent component of the macroscopic current.
引用
收藏
页码:219 / 229
页数:11
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