Figure 1: Determination and structure comparison of the coiled-coil assembly domain.

(a) Sequence alignment of the C-terminal cytoplasmic coiled-coil domain of Hv channel from various species. The positions of the coiled-coil heptad repeat (abcdefg) are indicated above the alignment. Coiled-coil residues occupying hydrophobic 'a' and 'd' positions are denoted by blue and red, respectively. Layer positions for each residue in the structure are indicated below the alignment. The green box depicts part of S4. (b) Oligomeric state of mHv1/VSOP channels studied by crosslinker analysis with western blotting. WT and C-terminus-truncated (ΔC) mHv1/VSOPs were expressed in HEK293 cells and treated with the indicated concentrations of DSS. (c) Comparison of the coiled-coil domain between mHv1/VSOP (violet) and hHv1/VSOP (green, PDB code: 3A2A). Two cartoon helix models are superimposed. Layer numbers and the N- and C-termini of the coiled-coil are indicated. The overall r.m.s. deviation of Cα atoms of each molecules (residues 222–262 of mouse versus 226–266 of human) is 0.798 Å, and that of the C-terminal half of the coiled-coil (235–262 of mouse versus 239–266 of human) is 0.377 Å. Right panel indicates the comparison of Asn in layer-3 between mHv1/VSOP (violet) and hHv1/VSOP (green) coiled-coils. Two structures (shown as stick and cartoon helix models) are superimposed. In hHv1/VSOP, the residue corresponding to N231 in mHv1/VSOP is N235.