TAILIEUCHUNG - Báo cáo khoa học: ` Inhibition of human ether a go-go potassium channels by 2+ Ca ⁄calmodulin binding to the cytosolic N- and C-termini

Humanether a` go-go potassium channels (hEAG1) open in response to membrane depolarization and they are inhibited by Ca 2+ ⁄calmodulin (CaM), presumably binding to the C-terminal domain of the channel sub-units. Deletion of the cytosolic N-terminal domain resulted in complete abolition of Ca 2+ ⁄CaM sensitivity suggesting the existence of further CaM binding sites. | iFEBS Journal Inhibition of human ether a go-go potassium channels by Ca2 calmodulin binding to the cytosolic N- and C-termini Ulrike Ziechner1 Roland Schonherr1 Anne-Kathrin Born1 Oxana Gavrilova-Ruch1 RalfW. Glaser2 Miroslav Malesevic3 Gerhard Kullertz3 and Stefan H. Heinemann1 1 Institute of Molecular CellBiology Research Unit Molecular and Cellular Biophysics Friedrich Schiller University Jena Germany 2 Department of Biochemistry and Biophysics Friedrich Schiller University Jena Germany 3 Max Planck Research Unit Enzymology of Protein Folding Halle Germany Keywords Calmodulin calcium potassium channel fluorescence correlation spectroscopy patch clamp Correspondence S. H. Heinemann Institute of Molecular Cell Biology Molecular and Cellular Biophysics Friedrich Schiller University Jena Drackendorfer Str. 1 D-07747 Jena Germany Fax 49 3641 9 32 56 82 Tel. 49 3641 9 32 56 80 E-mail Received 17 October 2005 revised 2 December 2005 accepted 10 January 2006 doi Human ether à go-go potassium channels hEAGl open in response to membrane depolarization and they are inhibited by Ca2 calmodulin CaM presumably binding to the C-terminal domain of the channel subunits. Deletion of the cytosolic N-terminal domain resulted in complete abolition of Ca2 CaM sensitivity suggesting the existence of further CaM binding sites. A peptide array-based screen of the entire cytosolic protein of hEAG1 identified three putative CaM-binding domains two in the C-terminus BD-C1 674-683 BD-C2 711-721 and one in the N-terminus BD-N 151-165 . Binding of GST-fusion proteins to Ca2 CaM was assayed with fluorescence correlation spectroscopy surface plasmon resonance spectroscopy and precipitation assays. In the presence of Ca2 BD-N and BD-C2 provided dissociation constants in the nanomolar range BD-C1 bound with lower affinity. Mutations in the binding domains reduced inhibition of the functional channels by Ca2 CaM. Employment of .

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