ABSTRACT
Research on gap junctions has followed the course of much of biology from purely descriptive morphology toward the integration of function with structure. The major questions that existed before the beginning of research into the biophysics of gap junctions centered around the concept that they were indeed channels between cells for the passage of low molecular weight metabolites, second messengers, and atomic ions. Analysis of channels in single membrane bilayers has proceeded rapidly by three electrophysiological methods. Analysis of function in small excised patches of membrane sealed to the tip of a glass pipette; Purification of putative channel components and reconstitution in planar bilayer membranes; and injection of frog oocytes with messenger RNA for the channel. Planar lipid bilayers have the advantages of control of composition and simplicity as liposomes and add the critical advantages of control of potential regulatory parameters such as voltage, pH, and calcium.
