Approximate structural model for the S-helix. A model of the S-Helix domain was constructed using other parallel CCs as templates (e.g. PDB: 1YSA). The sequence that was model was derived from the the logo shown in Fig. 2 and represents an idealized S-helix. The hydrophobic residues at position 'd' are shown as yellow spheres. The surface view is shown and the negatively charged ridges on the surface formed by 'b' and 'c' positions are shown in red. The hydrogen bonds, red dots, show the 'a'-'a' interaction of N10-N10; the R20-T21 interaction; the 'g'-'e' interactions of R16-E14 (Top) and E23-N28 (bottom).