Fig. 1. Cx43/ß-gal expression increased endogenous Cx43 expression. (A) Membrane-enriched fractions prepared from cells stably transfected with either ß-gal (con, lanes 1, 4) or Cx43/ß-gal (43ß1, lanes 2, 5; 43ß2, lane 3) were resolved by SDS-PAGE, transferred to PVDF and then immunoblotted using rabbit antisera to either Cx43 (lanes 1-3) or to ß-gal (4-5) and detected with enhanced chemiluminescence. The arrowhead indicates the band representing the Cx43/ß-gal fusion protein, while the arrow indicates ß-gal. The lower molecular mass band appearing in some samples of Cx43/ß-gal is a truncation product, as previously described (Sullivan and Lo, 1995). The 44 and 46 kDa Cx43 isoforms correspond to phosphorylated Cx43. Note the increase in amount of the faster migrating 42 kDa Cx43 isoform in cells expressing Cx43/ß-gal. The positions of molecular markers (kDa) are shown. (B) Immunoblots from 43ß1 and 43ß2 cells were quantified by densitometry to obtain the amount of Cx43/ß-gal expression relative to endogenous Cx43. Cx43/ß-gal expression by 43ß2 cells was five- to sixfold higher than for 43ß1 cells. (C) Immunoblots from control, 43ß1 and 43ß2 cells were quantified for the amount of the 42 kDa Cx43 isoform, normalized to the total level of Cx43 expressed by control cells. Values are means ± s.e.m. of triplicate preparations. *Statistically significant from control (P<0.05).