title: Solution structure of the NaV1.2 C-terminal EF-hand domain.
abstract: Voltage-gated sodium channels initiate the rapid upstroke of action potentials in many excitable tissues. Mutations within intracellular C-terminal sequences of specific channels underlie a diverse set of channelopathies, including cardiac arrhythmias and epilepsy syndromes. The three-dimensional structure of the C-terminal residues 1777-1882 of the human NaV1.2 voltage-gated sodium channel has been determined in solution by NMR spectroscopy at pH 7.4 and 290.5 K. The ordered structure extends from residues Leu-1790 to Glu-1868 and is composed of four alpha-helices separated by two short anti-parallel beta-strands; a less well defined helical region extends from residue Ser-1869 to Arg-1882, and a disordered N-terminal region encompasses residues 1777-1789. Although the structure has the overall architecture of a paired EF-hand domain, the NaV1.2 C-terminal domain does not bind Ca2+ through the canonical EF-hand loops, as evidenced by monitoring 1H,15N chemical shifts during aCa2+ titration. Backbone chemical shift resonance assignments and Ca2+ titration also were performed for the NaV1.5 (1773-1878) isoform, demonstrating similar secondary structure architecture and the absence of Ca2+ binding by the EF-hand loops. Clinically significant mutations identified in the C-terminal region of NaV1 sodium channels cluster in the helix I-IV interface and the helix II-III interhelical segment or in helices III and IV of the NaV1.2 (1777-1882) structure.
authors.affiliation: Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032-3702, USA.
authors.forename: Vesselin Z
authors.initials: VZ
authors.lastname: Miloushev
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Levine
authors.forename: Mark A
authors.initials: MA
authors.lastname: Arbing
authors.forename: John F
authors.initials: JF
authors.lastname: Hunt
authors.forename: Geoffrey S
authors.initials: GS
authors.lastname: Pitt
authors.forename: Arthur G
authors.initials: AG
authors.lastname: Palmer
mesh_terms: D000200:Action Potentials / Q000502:physiology; D001145:Arrhythmias, Cardiac / Q000235:genetics / Q000378:metabolism; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D004827:Epilepsy / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology; D009154:Mutation; D062551:NAV1.2 Voltage-Gated Sodium Channel; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding / Q000502:physiology; D017433:Protein Structure, Secondary / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D015222:Sodium Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013577:Syndrome
chemical_list: D062551:NAV1.2 Voltage-Gated Sodium Channel; D009419:Nerve Tissue Proteins; C568251:SCN2A protein, human; D015222:Sodium Channels; D002118:Calcium