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Fig. 5. Gating analysis of heterotypic wild-type and co-injected channels. Gj measurements recorded from oocyte paired to form heterotypic wild-type or coinjected gap junctions. (A) Cell pairs expressing wild-type Cx46 and Cx50 subunits form functional gap junctions with mean conductance values of 
22 µS, a level of coupling significantly higher than that of the water-injected negative control (P<0.05, Student's t-test). Co-injected heterotypic channels that expressed both wild-type and mutant Cx50 transcripts formed channels that displayed a 50% decrease in Gj when compared with wild-type heterotypic gap junctions, a level of coupling significantly higher than that of the background (P<0.05, Student's t-test). Data points represent individual conductance measurements. Columns indicate the mean ± s.e.m. (B,C) Junctional currents recorded from oocyte pairs were plotted as a function of time to compare heterotypic gap junctions expressing (B) wild-type Cx46 and Cx50 subunits and (C) heterotypic channels containing wild-type Cx46 and wild-type Cx50 and S50P mutant proteins. Representative Ij decays revealed that co-injected pairs appear more responsive at greater depolarizing voltage applications as well as more asymmetric than heterotypic channels comprising wild-type lens fiber connexins. Comparison of steady-state conductance properties. Equilibrium gating properties were analyzed by plotting normalized junctional conductance against transjunctional voltage and fit to the Boltzmann equation. (D) The steady-state reduction in conductance was greater for channels expressing both wild-type Cx50 and Cx50-S50P subunits (n=6) when compared with that of the heterotypic wild-type channel (n=5), indicating an increase in voltage-gating sensitivity for heterotypic channels containing the mutant protein.
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