Fast and slow gating are inherent properties of the pore module of the K+ channel Kcv.
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.
Abenavoli
Alessandra
A
Dipartimento di Biologia and Istituto di Biofisica-Consiglio Nazionale delle Ricerche, Università degli Studi di Milano, 20133 Milan, Italy.
DiFrancesco
Mattia Lorenzo
ML
Schroeder
Indra
I
Epimashko
Svetlana
S
Gazzarrini
Sabrina
S
Hansen
Ulf Peter
UP
Thiel
Gerhard
G
Moroni
Anna
A
D000818:Animals; D015640:Ion Channel Gating; D009865:Oocytes; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000378:metabolism*; D014764:Viral Proteins / Q000378:metabolism*; D014982:Xenopus laevis
C405463:Kcv potassium channel, Chlorella virus; D015221:Potassium Channels; D014764:Viral Proteins