Cell/cell channel formation involves disulfide exchange.
The oocyte cell/cell-channel assay was used to identify amino acids involved in the process of cell/cell-channel formation. The expression of the rat liver gap-junction protein, connexin 32, in single oocytes, results in the accumulation of a pool of channel precursors. Upon pairing of such oocytes, cell/cell channels form rapidly from this pool. The rate of formation is affected by thiol-specific reagents and the pH. This suggests the involvement of extracellular cysteine residues in the channel formation process. Two connexin-32 mutants were generated by site-directed mutagenesis in which cysteine residues were replaced by serine. Both mutant connexins were unable to form cell/cell channels. Thus, the cysteine residues appear to play an important role in the channel formation process.
Dahl
G
G
Department of Physiology, University of Miami School of Medicine, Florida 33101.
Levine
E
E
Rabadan-Diehl
C
C
Werner
R
R
D000818:Animals; D002450:Cell Communication; D017630:Connexins; D004220:Disulfides / Q000378:metabolism*; D004553:Electric Conductivity; D005260:Female; D066298:In Vitro Techniques; D007365:Intercellular Junctions / Q000502:physiology*; D007473:Ion Channels / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D016254:Mutagenesis, Insertional; D009865:Oocytes / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D014158:Transcription, Genetic
D017630:Connexins; D004220:Disulfides; D007473:Ion Channels; D008565:Membrane Proteins; D012333:RNA, Messenger