ABSTRACT
Modern electrophysiology and membrane biophysics trace their origins to the demonstration that membrane conductance of squid axon was strongly altered when membrane potential was varied over a narrow voltage range. The membrane proteins comprising voltage-dependent ion channels have been probed with techniques of biochemistry, immunology, and molecular biology. As techniques of molecular biology have clarified the primary structures of various gap junction proteins, termed connexins, it has become possible to propose a structural framework for locations of gating domains within the gap junction channel. The chapter summarizes what is known of transjunctional voltage dependence of gap junction channels. It stresses two systems, the amphibian embryo, where voltage dependence has been studied most extensively, and the rat liver, in which voltage dependence has been found using a combination of studies in hepatocyte pairs and in exogenous expression systems.
