Molecular analysis of voltage dependence of heterotypic gap junctions formed by connexins 26 and 32

摘要: Heterotypic gap junctions formed by pairing Xenopus oocytes expressing hemichannels of Cx32 with those Cx26 displayed novel transjunctional voltage (Vj) dependence not predicted the behavior these connexins in homotypic configurations. Rectification initial and steady-state currents was observed. Relative positivity negativity on side junction resulted increased decreased conductance (gj0), respectively. Only relative (gj infinity). This suggested that interactions between influences gating. The role first extracellular loop (E1) examined a chimeric connexin which E1 replaced (Cx32*26E1). Both rectified gj0/Vj relations were less steep than observed for Cx32/Cx26. Decreases gj infinity occurred either polarity Vj Cx32/Cx32*26E1 junction. Mutation two amino acids steepness both infinity/Vj relations. These data demonstrate fast rectification can arise from mismatched domains may contribute to sensing mechanisms underlying slow Vj-dependent processes.