Structural elements of L1 important for papillomavirus particle assembly. A) The top view of an L1 pentamer, showing the lateral projections from each of the five monomers (each in a discreet color). B) A close-up view of the lateral projections two monomers, showing the detailed positions of h2, h3, h4, and h5 at the C-terminus of L1. C) The inter-pentameric helix-helix interactions between two pentamers in the T = 1 particle. The h4 of one pentamer (in yellow) interacts with h2 and h3 of another pentamer (in pink).