GRAMICIDIN CHANNELS - A SOLVABLE MEMBRANE-PROTEIN FOLDING PROBLEM

The linear gramicidins are peptide antibiotics that form cation-select ive channels in lipid bilayers. Gramicidin channels have very well-def ined functional characteristics, and the structure of membrane-spannin g gramicidin A channels is known at atomic resolution. These features make the gramicidins well suited to study how the amino acid sequence encodes the structure and function of a membrane-spanning channel. We show how one can use electrophysiological measurements to obtain struc tural information about conducting channels and to quantify the confor mational preferences of sequence-substituted gramicidin mutants.