Kinetics of Gramicidin Channel Formation in Lipid Bilayers: Transmembrane Monomer Association
- 30 November 1990
- journal article
- research article
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 250 (4985) , 1256-1259
- https://doi.org/10.1126/science.1700867
Abstract
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.Keywords
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