Structures of member capsid proteins of the PRD1-adenovirus lineage. (a) The structures are STIV (Sulfolobus turreted icosahedral virus, cyan), human adenovirus (purple), bacteriophage PRD1 (green), bacteriophage PM2 (blue), and Paramecium bursaria chlorella virus type 1 (PBCV-1, red). (b) The structure of the PRD1 virion, which forms a T = 25 capsid. The inset shows the trimeric capsomer with the individual monomers indicated. Figure adapted from ref. 120 with permission from Nature Publishing Group, copyright 2008.