title: Shortened analog of the gramicidin A channel argues for the doubly occupied channel as the dominant conducting state.
abstract: A shortened analog of the gramicidin A transmembrane channel has been synthesized and its transport characterized in planar lipid bilayer membranes. General considerations of a shorter diffusional length and a shorter distance over which the voltage drop occurs (i.e., an increased electric field) would contribute to an increase in single-channel conductance. The finding of a decreased single-channel conductance supports the perspective that the dominant conducting state is the doubly occupied channel wherein distance-dependent repulsion due to the first ion in the channel impedes entry of the second ion in the shorter channel.
mesh_terms: D000595:Amino Acid Sequence; D004553:Electric Conductivity; D006096:Gramicidin; D007473:Ion Channels; D007476:Ionophores; D013329:Structure-Activity Relationship
chemical_list: D007473:Ion Channels; D007476:Ionophores; D006096:Gramicidin