Figure 1. Predicted helical packing arrangement and crystal structure of Halorhodopsin (1E12:A).

In this example the two left-most helices share the same interactions. The correct arrangement has been identified as having no same-side loop crossovers, compared to one for the incorrect arrangement. Predicted residue-residue contacts are annotated on the packing arrangement while observed helix-helix interactions are annotated on the crystal structure.