Wissmann, R. and Baukrowitz, T. and Kalbacher, H. and Kalbitzer, Hans Robert and Ruppersberg, J. P. and Pongs, O. and Antz, C. and Fakler, B. (1999) NMR structure and functional characteristics of the hydrophilic N terminus of the potassium channel beta-subunit Kvbeta1.1. The Journal of biological chemistry 274 (50), pp. 35521-35525.
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Rapid N-type inactivation of voltage-dependent potassium (Kv) channels controls membrane excitability and signal propagation in central neurons and is mediated by protein domains (inactivation gates) occluding the open channel pore from the cytoplasmic side. Inactivation domains (ID) are donated either by the pore-forming alpha-subunit or certain auxiliary beta-subunits. Upon coexpression, Kvbeta1.1 was found to endow non-inactivating members of the Kv1alpha family with fast inactivation via its unique N terminus. Here we investigated structure and functional properties of the Kvbeta1.1 N terminus (amino acids 1-62, betaN-(1-62)) using NMR spectroscopy and patch clamp recordings. betaN-(1-62) showed all hallmarks of N-type inactivation: it inactivated non-inactivating Kv1.1 channels when applied to the cytoplasmic side as a synthetic peptide, and its interaction with the alpha-subunit was competed with tetraethylammonium and displayed an affinity in the lower micromolar range. In aequous and physiological salt solution, betaN-(1-62) showed no well defined three-dimensional structure, it rather existed in a fast equilibrium of multiple weakly structured states. These structural and functional properties of betaN-(1-62) closely resemble those of the "unstructured" ID from Shaker B, but differ markedly from those of the compactly folded ID of the Kv3.4 alpha-subunit.
|Institutions:||Biology, Preclinical Medicine > Institut für Biophysik und physikalische Biochemie > Prof. Dr. Dr. Hans Robert Kalbitzer|
|Subjects:||500 Science > 570 Life sciences|
|Created at the University of Regensburg:||Unknown|
|Deposited On:||13 Sep 2010 08:08|
|Last Modified:||13 Sep 2010 08:08|