Fig. 1. Cx50-S50P fails to form functional intercellular channels. (A,B) Immunoblot analysis of oocytes showed equivalent levels of wild-type and mutant connexin expression for all conditions tested. (C,D) Band densitometry quantitatively confirmed that mean protein expression was not significantly changed (P>0.05, Student's t-test). (E) Junctional conductance measurements recorded from Xenopus oocyte pairs injected with wild-type Cx50, Cx46 or S50P transcripts alone or in combination. Cell pairs expressing wild-type Cx50 or Cx46 subunits alone form functional gap junctions with mean conductance values of 26 µS or 20 µS, respectively. Oocytes co-injected with both wild-type and mutant Cx50 transcripts formed channels that displayed a 20% decrease in G_j when compared with homotypic Cx50 gap junctions, a level of coupling significantly higher than that of the background (P<0.05, Student's t-test) but not significantly different from homotypic Cx50 channels (P>0.05, Student's t-test). Similarly, the co-expression of Cx46 and Cx50-S50P subunits did not significantly alter junctional conductance (P>0.05, Student's t-test) as these channels exhibited a mean G_j of 17 µS. Heterotypic channels failed to form functional channels with levels of conductance significantly higher than that of the water injected negative controls (P>0.05, Student's t-test). Cx50-S50P subunits alone failed to produce functional intercellular channels. Data points represent individual conductance measurements. Columns indicate the mean ± s.e.m.