Gating properties of connexin32 cell-cell channels and their mutants expressed in Xenopus oocytes.
Carboxyl-terminal deletion mutants of the gap junction protein connexin32 were tested in the oocyte cell-cell channel assay. Oocytes expressing a mutant lacking 58 carboxyl terminal amino acids were found to exhibit junctional conductances of the same magnitude as oocytes expressing wild-type connexin32. The gating properties of the channels formed by this mutant of connexin32 with respect to transjunctional voltage and cytoplasmic acidification are indistinguishable from those found with wild-type connexin32 channels. This includes a novel pH-dependent voltage gate. In another mutant, two carboxyl terminal serine residues, Ser233 and Ser240, were replaced by Asn residues. This double mutant has properties indistinguishable from wild-type connexin32, suggesting that phosphorylation of either of these serines is not required for channel opening.
Werner
R
R
Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, Florida 33101.
Levine
E
E
Rabadan-Diehl
C
C
Dahl
G
G
D000818:Animals; D001665:Binding Sites; D002245:Carbon Dioxide / Q000378:metabolism; D002872:Chromosome Deletion; D017630:Connexins; D004553:Electric Conductivity; D005260:Female; D007365:Intercellular Junctions / Q000378:metabolism*; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009865:Oocytes / Q000378:metabolism; D014982:Xenopus laevis
D017630:Connexins; D008565:Membrane Proteins; D002245:Carbon Dioxide