<p>The major capsid proteins (vp54 and vp72) found in Iridoviruses, Phycodnaviruses, Asfarviruses and Ascoviruses share the same structure. All these viruses are type II dsDNA viruses with no RNA stage. This is the most abundant structural protein and can account for up to 45% of virion protein [<cite idref="PUB00010097"/>]. The structure of vp54 has been determined from <taxon tax_id="10506">Paramecium bursaria Chlorella virus 1</taxon> (PBCV-1), a very large icosahedral virus containing an internal membrane enclosed within a glycoprotein coat. The vp54 protein is a duplication consisting of two domains with a similar fold packed together like the nucleoplasmin subunits. The vp54 protein forms a trimer, where the domains are arranged around a pseudo 6-fold axis. The domains have a beta-sandwich structure consisting of 8 strands in two sheets with a jelly-roll topology [<cite idref="PUB00022136"/>].</p><p>This entry represents a structural subdomain with a distorted beta-sandwich topology.</p> Major coat protein vp54/vp72, sandwich subdomain, dsDNA virus