Homologous Superfamily

Herpesvirus major capsid protein, upper domain superfamily (IPR023233)

Short name: Herpes_MCP_upper_sf


The Herpesvirus major capsid protein (MCP) is the principal protein of the icosahedral capsid, forming the main component of the hexavalent and probably the pentavalent capsomeres. The capsid shell consists of 150 MCP hexamers and 12 MCP pentamers. One pentamer is found at each of the 12 apices of the icosahedral shell, and the hexamers form the edges and 20 faces [PMID: 11222712]. The MCP can be considered as having three domains: floor, middle and upper. The floor domains form a thin largely continuous layer, or shell, and are the only parts that interact directly to form intercapsomeric connections. They also interact with the internal scaffolding protein during capsid assembly [PMID: 7583656]. The remainder of the protein extends radially outward from the capsid producing the hexamer and pentamer capsomere structures. The middle domains are involved in binding to the triplexes that lie between and link adjacent capsomeres [PMID: 10797014]. The upper domains form the tops of the hexamer and pentamer towers and are the binding sites for the small capsid protein VP26 in the hexons and for tegument proteins in the pentons.

The upper domain of MCP forms a pyramid structure composed predominantly of loops and alpha-helices [PMID: 12574112]. This domain appears to form a compact, stable structure and may act as a rigid core around which the more flexible middle and floor domains are able to undertake the conformational changes required for capsid assembly.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.