Kinetics of gramicidin channel formation in lipid bilayers: transmembrane monomer association.
Conducting gramicidin channels form predominantly by the transmembrane association of monomers, one from each side of a lipid bilayer. In single-channel experiments in planar bilayers the two gramicidin analogs, [Val1]gramicidin A (gA) and [4,4,4-F3-Val1]gramicidin A (F3gA), form dimeric channels that are structurally equivalent and have characteristically different conductances. When these gramicidins were added asymmetrically, one to each side of a preformed bilayer, the predominant channel type was the hybrid channel, formed between two chemically dissimilar monomers. These channels formed by the association of monomers residing in each half of the membrane. These results also indicate that the hydrophobic gramicidins are surprisingly membrane impermeant, a conclusion that was confirmed in experiments in which gA was added asymmetrically and symmetrically to preformed bilayers.
Department of Physiology and Biophysics, Cornell University Medical College, New York, NY 10021.
A M
AM
O'Connell
R E
RE
Koeppe
O S
OS
Andersen
D000595:Amino Acid Sequence; D002463:Cell Membrane Permeability; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004553:Electric Conductivity; D006096:Gramicidin / Q000737:chemistry* / Q000378:metabolism; D007473:Ion Channels / Q000737:chemistry* / Q000502:physiology; D007700:Kinetics; D008051:Lipid Bilayers / Q000737:chemistry*; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D011487:Protein Conformation
D007473:Ion Channels; D008051:Lipid Bilayers; D046911:Macromolecular Substances; D006096:Gramicidin