title: pH-dependent intramolecular binding and structure involving Cx43 cytoplasmic domains.
abstract: pH-induced closure of connexin43 (Cx43) channels involves interaction of the Cx43 carboxyl-terminal (Cx43CT) with a separate "receptor" domain. The receptor location and structure and whether the interaction is directly intramolecular are unknown. Here we show resonant mirror technology, enzyme-linked sorbent assays, and nuclear magnetic resonance (NMR) experiments demonstrating pH-dependent binding of Cx43CT to region 119-144 of Cx43 (Cx43L2), which we propose is the receptor. NMR showed that acidification induced alpha-helical order in Cx43L2, whereas only a minor modification in Cx43CT structure was detected. These data provide the first demonstration of chemically induced structural order and binding between cytoplasmic connexin domains.
authors.affiliation: Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
authors.forename: Heather S
authors.initials: HS
authors.lastname: Duffy
authors.forename: Paul L
authors.initials: PL
authors.lastname: Sorgen
authors.forename: Mark E
authors.initials: ME
authors.lastname: Girvin
authors.forename: Phyllis
authors.initials: P
authors.lastname: O'Donnell
authors.forename: Wanda
authors.initials: W
authors.lastname: Coombs
authors.forename: Steven M
authors.initials: SM
authors.lastname: Taffet
authors.forename: Mario
authors.initials: M
authors.lastname: Delmar
authors.forename: David C
authors.initials: DC
authors.lastname: Spray
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D018031:Connexin 43 / Q000737:chemistry* / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D004058:Diffusion; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D005982:Glutathione Transferase / Q000378:metabolism; D006639:Histidine / Q000737:chemistry; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010452:Peptide Biosynthesis; D010455:Peptides / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D013997:Time Factors
chemical_list: D018031:Connexin 43; D010455:Peptides; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D006639:Histidine; D005982:Glutathione Transferase