title: C-Linker Accounts for Differential Sensitivity of ERG1 and ERG2 K+ Channels to RPR260243-Induced Slow Deactivation.
abstract: Compounds can activate human ether-à-go-go-related gene 1 (hERG1) channels by several different mechanisms, including a slowing of deactivation, an increase in single channel open probability, or a reduction in C-type inactivation. The first hERG1 activator to be discovered, RPR260243 ((3R,4R)-4-[3-(6-methoxyquinolin-4-yl)-3-oxo-propyl]-1-[3-(2,3,5-trifluorophenyl)-prop-2-ynyl]-piperidine-3-carboxylic acid) (RPR) induces a pronounced, voltage-dependent slowing of hERG1 deactivation. The putative binding site for RPR, previously mapped to a hydrophobic pocket located between two adjacent subunits, is fully conserved in the closely related rat ether-à-go-go-related gene 2 (rERG2), yet these channels are relatively insensitive to RPR. Here, we use site-directed mutagenesis and heterologous expression of channels in Xenopus oocytes to characterize the structural basis for the differential sensitivity of hERG1 and rERG2 channels to RPR. Analysis of hERG1-rERG2 chimeric channels indicated that the structural determinant of channel sensitivity to RPR was located within the cytoplasmic C-terminus. Analysis of a panel of mutant hERG1 and rERG2 channels further revealed that seven residues, five in the C-linker and two in the adjacent region of the cyclic nucleotide-binding homology domain, can fully account for the differential sensitivity of hERG1 and rERG2 channels to RPR. These findings provide further evidence that the C-linker is a key structural component of slow deactivation in ether-à-go-go-related gene channels.
authors.affiliation: Nora Eccles Harrison Cardiovascular Research and Training Institute (A.G., M.C.S.) and Department of Internal Medicine, Division of Cardiovascular Medicine (M.C.S.), University of Utah, Salt Lake City, Utah.
authors.forename: Alison
authors.initials: A
authors.lastname: Gardner
authors.affiliation: Nora Eccles Harrison Cardiovascular Research and Training Institute (A.G., M.C.S.) and Department of Internal Medicine, Division of Cardiovascular Medicine (M.C.S.), University of Utah, Salt Lake City, Utah sanguinetti@cvrti.utah.edu.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Sanguinetti
mesh_terms: D000818:Animals; D001665:Binding Sites; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010880:Piperidines / Q000494:pharmacology*; D011487:Protein Conformation; D011804:Quinolines / Q000494:pharmacology*; D051381:Rats; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics / Q000378:metabolism
chemical_list: D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; C000606913:KCNH2 protein, human; C092509:KCNH6 protein, human; D010880:Piperidines; D011804:Quinolines; C499186:RPR260243