A novel explanation for fluctuations of ion current through narrow pores.
Fluctuation of ion current, between a high conductance and a low conductance state, through biological ion channels and pores is assumed to arise from conformational changes between an "open" and a "closed" configuration. Here we offer an additional mechanism that arises from changes in ionization of fixed charges within, or at the mouth of, a channel or pore. Our hypothesis, which is based on measurements of ion selectivity alongside ion current, applies to pores through some synthetic membranes and through channels-such as those created by certain toxins-that remain (at least partially) open in the low conductance state. It may also explain the phenomena of "open channel noise" and "substate behavior" that characterize several endogenous ion channels and should be considered when modeling the behavior of such channels.
Korchev
Y E
YE
Department of Physiology, Charing Cross and Westminister Medical School, University of London, U.K.
Bashford
C L
CL
Alder
G M
GM
Apel
P Y
PY
Edmonds
D T
DT
Lev
A A
AA
Nandi
K
K
Zima
A V
AV
Pasternak
C A
CA
D001427:Bacterial Toxins / Q000494:pharmacology; D004553:Electric Conductivity; D006460:Hemolysin Proteins / Q000494:pharmacology; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D007477:Ions; D008567:Membranes, Artificial; D011093:Polyethylene Terephthalates
D001427:Bacterial Toxins; D006460:Hemolysin Proteins; D007473:Ion Channels; D007477:Ions; D008567:Membranes, Artificial; D011093:Polyethylene Terephthalates; C021091:staphylococcal alpha-toxin