Fig. 3. Functional analysis of wildtype and Cx43 amino-acid substitution variants. Connexin-expressing BHK cells with assembled connexin clusters detectable by auto-fluorescence of their GFP-tags (GFP) were microinjected with a mixture of lucifer yellow (LY) and rhodamine dextran (RD), and their capacity to transfer LY to the neighboring cells was investigated. Although all Cx43 variants assembled into clusters, only Cx43 wt channels (row 2) and channels assembled from the R153W (P4) variant (row 7) transferred dye. BHK wild-type cells injected as controls (row 1) showed no dye coupling. Representative cells were imaged before and after microinjection (dye-filled injection capillaries visible on the LY images are marked with arrows). RD co-injected into the control did not pass to neighboring cells, indicating that cells were not leaking dye. Phase contrast images are shown on the left.