Clustering of connexin 43-enhanced green fluorescent protein gap junction channels and functional coupling in living cells

Communication-incompetent cell lines were transfected with connexin (Cx) 43 fused with enhanced green fluorescent protein (EGFP) to examine the relati on between Cx distribution determined by fluorescence microscopy and electr ical coupling measured at single-channel resolution in living cell pairs, C x43-EGFP channel properties were like those of wild-type Cx43 except for re duced sensitivity to transjunctional voltage. Cx43-EGFP clustered into plaq ues at locations of cell-cell contact. Coupling was always absent in the ab sence of plaques and even in the presence of small plaques. Plaques exceedi ng several hundred channels always conferred coupling, but only a small fra ction of channels were functional, These data indicate that clustering may be a requirement for opening of gap junction channels.