Figure 1.

Cartoon of a parallel two-stranded coiled coil. (a) Side view and (b) top view. The interface between the α-helices in a coiled-coil structure is formed by residues at the core positions a, d, e and g. Positions in the two helices are distinguished by the prime notation; for example, a and a' are analogous positions in the two helices. N, amino terminus; C, carboxy terminus.