Authors: C Peracchia XG Wang LL Peracchia
Publish Date: 2014/03/18
Volume: 178, Issue: 1, Pages: 55-70
Abstract
Certain COOHterminus mutants of connexin32 Cx32 were previously shown to form channels with unusual transjuctional voltage V j sensitivity when tested heterotypically in oocytes against Cx32 wild type Junctional conductance G j slowly increased by severalfold or decreases to nearly zero with V j positive or negative respectively at mutant side and V j positive at mutant side reversed CO2induced uncoupling This suggested that the CO2sensitive gate might be a V j sensitive slow gate Based on previous data for calmodulin CaM involvement in gap junction function we have hypothesized that the slow gate could be a CaMlike pore plugging molecule cork gating model This study describes a similar behavior in heterotypic channels between Cx32 and each of four new Cx32 mutants modified in cytoplasmicloop and/or COOHterminus residues The mutants are ML/NN+3R/N 3R/N ML/NN and ML/EE in these mutants N or E replace M105 and L106 and N replace R215 R219 and R220 This study also reports that inhibition of CaM expression strongly reduces V j and CO2 sensitivities of two of the most effective mutants suggesting a CaM role in slow and chemical gating
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