Schematic of a Parallel Dimeric Coiled Coil

<div><p>(A) Helical-wheel representation shows an end-on view of the structure. Opposing <b>a</b> and <b>d</b> residues interact in the core while opposing <b>e</b> and <b>g</b> residues frequently participate in electrostatic interactions.</p><p>(B) Cartoon representation of the coiled coil, viewed from the side. Residues are represented as spheres. An <b>e</b> position is better located for interaction with the <b>g</b> position of the previous heptad on the opposing strand than with the <b>g</b> position of the next heptad (bold arrows). This interaction is denoted <b>g-e′+</b>, and coupling energies for it have been determined experimentally [<a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.0020063#pcbi-0020063-b024" target="_blank">24</a>].</p>