FIGURE 5.

CCN3 binds to the cytoplasmic tail of gap junction protein Cx43. A, immunofluorescence image showing the co-staining of endogenous CCN3 with Cx43 only in Hs578T cells overexpressing full-length Cx43 (white arrowheads) and not in C-tail truncated Cx43 (Cx43) or GFP-expressing cells. Blue, 4′,6-diamidino-2-phenylindole staining. Scale bar, 10 μm. B, Cx43 deletion mutants used as competing antigens in a co-IP assay using anti-CCN3 antibody. The presence of endogenous Cx43 in A–C showed that these proteins cannot replace endogenous Cx43 in the co-immunoprecipitation and thereby most likely have lost the CCN3-interacting sites.