title: Low conductance states of a single ion channel are not 'closed'.
abstract: We have used a polymer-exclusion method to estimate the sizes of the high- and low-conductance states of Staphylococcus aureus alpha-toxin channels across planar lipid bilayers. Despite a > 10-fold difference in conductance between high- and low-conductance states, the size differs by < 2-fold. We conclude that factors other than the dimensions have a strong influence on the conductance of alpha-toxin channels. We also show that the high conductance state is destabilized by the presence of high molecular weight polymers outside the channel, compatible with the removal of channel water as the high conductance state "shrinks" to the low conductance state.
authors.affiliation: Department of Cellular & Molecular Sciences, St George's Hospital Medical School, London, UK.
authors.forename: Y E
authors.initials: YE
authors.lastname: Korchev
authors.forename: C L
authors.initials: CL
authors.lastname: Bashford
authors.forename: G M
authors.initials: GM
authors.lastname: Alder
authors.forename: J J
authors.initials: JJ
authors.lastname: Kasianowicz
authors.forename: C A
authors.initials: CA
authors.lastname: Pasternak
mesh_terms: D001693:Biological Transport, Active; D015640:Ion Channel Gating; D007473:Ion Channels / Q000378:metabolism; D008051:Lipid Bilayers / Q000378:metabolism; D013211:Staphylococcus aureus / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism*
chemical_list: D007473:Ion Channels; D008051:Lipid Bilayers; D010738:Type C Phospholipases