PHYSICAL CHARACTERIZATION OF GAP JUNCTION MEMBRANE CONNEXONS (HEMI-CHANNELS) ISOLATED FROM RAT-LIVER

Enriched subcellular fractions of double membrane gap junctions (plaqu es) from rat livers were treated under reducing conditions with high s alt and non-ionic detergent concentrations at high pH to obtain a prep aration of structural 80-90 Angstrom complexes of oligomers (connexons ). The isolated oligomers were chromatographically purified, and subse quently characterized immunologically, morphologically by electron mic roscopy, hydrodynamically by gel filtration and ultracentrifugation, s pectroscopically by circular dichroism, and chemically via cross-linki ng studies. The physical characteristics of these isolated gap junctio n complexes were compared to those of native membrane-bound gap juncti ons in rat liver. These analyses indicate that the isolated complex (c onnexon) principally contains a hexameric arrangement of gap junction protein to form a single membrane hemi channel.