Transmembrane channels and their characterization in phospholipid structures

Fundamental aspects of cation hydration and lipid layer permeation are considered. The molecular structure of the gramicidin A transmembrane channel is treated in the context of a model for physiological channels and in the context of extensions in the knowledge of channel mechanisms which are derivable from studies of this first-described monovalent cation selective channel. It is demonstrated that gramicidin A channel structures can be incorporated into lysolecithin micelles and are found to exhibit properties of sodium exchange which are similar to those of transmemberane channels characterzed by means of electrical studies on planar lipid layers. A working model is presented for the packaging of channels in micelles.