Fig. 7.

Charge reversal at R33 or E162 reduces intercellular transfer of Neurobiotin. A Left, schematic diagram illustrating the intercellular transfer of a gap junction tracer (shown in yellow) from a microinjected cell to its neighboring coupled cells when gap junction channels are open (paired green lines). Right, schematic diagram illustrating the lack of intercellular transfer of a gap junction tracer (shown in yellow) from a microinjected cell to its neighboring cells when cells are uncoupled (red Xs in between the cells). B Photomicrographs show representative examples of intercellular transfer of Neurobiotin in HeLa, HeLa-Cx50, HeLa-Cx50R33E, HeLa-Cx50E162R and HeLa-Cx50R33E,E162R cells after microinjection of the tracer into one cell of the cluster (indicated by the red asterisk). C Bar graph shows the quantification of intercellular transfer of Neurobiotin in untransfected HeLa cells (HeLa) and HeLa cells stably transfected with Cx50, Cx50R33E, Cx50E162R or Cx50R33E,E162R. The results are presented as mean (bar) ± S.E.M. (error bars). A minimum of ten independent microinjections were analyzed (n = 15 for HeLa, 24 for Cx50, 13 for Cx50R33E, and 10 for Cx50E162R and Cx50R33E,E162R). Asterisks indicate significant differences vs. HeLa cells (p < 0.012); ^#indicates significant differences vs. HeLa-Cx50 cells (p < 10^–9)