Fig. 3.

EGFP-Cx43 in HeLa cells reaches the cell surface and forms plaques but no functional hemichannels or channels. (A) A pair of EGFP-Cx43 cells forms a fluorescent plaque typical of a gap junction (arrow). (B) Application of voltage ramps (Lower) to cell 1 did not induce junctional currents in the other cell (Upper). (C) Phase. (D) Fluorescence of an isolated EGFP-Cx43 cell shows expression at the surface membrane. (E) Two records of polarization to +90 mV show no Cx43-like single-channel activity (an ≈20-pA step would be seen after opening of a 220-pS Cx43 channel; see Fig. 2).