The structure of cell membranes involved in intercellular communication.

The molecular structure of mouse hepatocyte gap junctions is investigated with corrlated electron microscopy, biochemistry, and x-ray diffraction technics. These studies reveal that the gap junction is composed of a hexagonal lattice of protein subunits, connexons, which pierce the hydrophobic membrane and establish a structural basis for intercellular hydrophilic channels or pores. By digesting liver-cell membranes with trypsin, a preparation of open- and closed-gap junction vesicles can be generated; this preparation will permit direct permeability measurements across the gap junction membranes in an in-vitro system.