Fig. 4.

Cx37-C61,65A does not form functional gap junction channels. A iRin cell pairs induced to express Cx37-WT (37-WT dox+) were variably coupled, with g_j commonly between 1 and 5 nS. In contrast, induced and noninduced iRin37-C61,65A cells were not detectably coupled (data from 1C3 and 1D2 clones). Notice that all of the iRin37-C61,65A cell pairs evaluated, whether induced or noninduced, had g_j values <0.3 nS, which is not different from electrical noise at these recording settings. B, C Single-channel events from iRin37 dox+ recorded in external solutions containing either normal (B) or low (C) calcium, as described in the dye-uptake protocol. Notice that channel flickering decreased upon introduction of low external calcium so that transitions corresponding to ~300 pS and substates corresponding to ~80 pS were readily apparent. Downward black and gray arrows indicate the start and end of the voltage pulse, respectively