Fig. 2.

Hetero-hexamer building blocks. a An icosahedral asymmetric unit, viewed from the inside. VP4 is blue, VP7 green and VP9 magenta. The hexamers are labelled and the arrows show close-ups of a type III turret (upper) with one VP7−VP4 building block highlighted in purple. The N-termini of VP7 are marked by green ellipses and the side chain of Phe 155 of VP4 shown and circled in orange. b The three distinct environments of Phe 155 (shown in green, yellow and orange from left to right, with the neighbouring subunits coloured differently). c Capsid coloured according to hexamer type: cyan—5-fold adjacent (type III); dark blue—central (type III); pale cyan—3-fold adjacent (type III); red—2-fold adjacent (type II); yellow—2-fold adjacent (type III). VP9 is shown in magenta. One icosahedral asymmetric unit is outlined