title: Construction of a Ca(2+)-gated artificial channel by fusing alamethicin with a calmodulin-derived extramembrane segment.
abstract: Using native chemical ligation, we constructed a Ca(2+)-gated fusion channel protein consisting of alamethicin and the C-terminal domain of calmodulin. At pH 5.4 and in the absence of Ca(2+), this fusion protein yielded a burst-like channel current with no discrete channel conductance levels. However, Ca(2+) significantly lengthened the specific channel open state and increased the mean channel current, while Mg(2+) produced no significant changes in the channel current. On the basis of 8-anilinonaphthalene-1-sulfonic acid (ANS) fluorescent measurement, Ca(2+)-stimulated gating may be related to an increased surface hydrophobicity of the extramembrane segment of the fusion protein.
authors.affiliation: Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Noshiro
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Sonomura
authors.forename: Hao-Hsin
authors.initials: HH
authors.lastname: Yu
authors.forename: Miki
authors.initials: M
authors.lastname: Imanishi
authors.forename: Koji
authors.initials: K
authors.lastname: Asami
authors.forename: Shiroh
authors.initials: S
authors.lastname: Futaki
mesh_terms: D000408:Alamethicin / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D002147:Calmodulin / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D060326:Chemistry Techniques, Synthetic; D031541:Fluorescence Resonance Energy Transfer; D015640:Ion Channel Gating; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017434:Protein Structure, Tertiary
chemical_list: D015220:Calcium Channels; D002147:Calmodulin; D000408:Alamethicin; D002118:Calcium