A. Seven-bladed β-propeller (1got) coloured according to the WD repeats. B. Backbone representation of the superimposed WD repeat template structures (1erj—red, 1got—green, 1gxr—blue, 1k8k—yellow, 1pgu—magenta, 1p22—cyan, 1sq9—grey). C. A cartoon representation of a β-propeller. The structure is different in radius on the “top” and “bottom”. The narrower side is defined as the “top” region in this report. Both A and B show the top surface. The strands a-d form seven blades of the propeller structure.