Fig. 3. Features of the hexon channel.
(A) β-sheet augmentations between neighboring channel domains result in six β-strands from one MCP channel domain interacting with β22 from an adjacent channel domain to form a seven-stranded β-sheet. (B) Six seven-stranded β-sheets form a daisy chain–like β-sheet ring (inset) around the hexon channel, connected by six constricting loops that define the narrowest region of the channel. (C) Electrostatic surface rendering of a clipped hexon channel. Blue and red denote positive and negative charge, respectively. (D) Top view of (C), showing that upper channel regions are predominantly negatively charged. (E) Bottom view of (C), showing that DNA-accommodating lower channel regions are predominantly positively charged.