Figure 2.

Exploiting the TR transition in supramolecular protein engineering. (A) Schematic representation of the three types of zinc insulin hexamers, designated T₆, T₃R^f₃, and R₆. Residues B1–B8 exhibit a change in secondary structure as shown in black. T-state protomers are otherwise shown in red, and R-state protomers in blue. (B) Corresponding ribbon representation of wild-type crystal structures. Axial zinc ions are shown in blue-gray. Coordinates were obtained from Protein Databank entries 4INS, 1TRZ, and 1ZNJ, respectively. This figure is reprinted by Wan and colleagues ¹¹⁷ with permission of the authors.