Capsid protein that self-assembles to form the pseudo-hexameric capsomers of the icosahedral capsid (PubMed:31624094). The capsid is constructed of 2760 pseudo-hexameric capsomers and 12 pentameric capsomers, with a T=277 symmetry, about 200 nm in diameter (PubMed:31624094). The capsid encapsulates the DNA-containing nucleoid, the core shell and the inner membrane (PubMed:9580160). Plays an essential role in virion assembly (PubMed:9580160). Involved in virus attachment to the host cell (PubMed:8764090). Homotrimer (PubMed:31624094). The membrane-bound form, but not the cytosolic one, assembles into large complexes (PubMed:9573294). Interacts with the minor capsid proteins M1249L and p17; these interactions form a rigid zipper structure that stabilizes the capsomers (PubMed:31624094). Present in the outer part of the capsid shell (PubMed:31624094). Localizes to the viral factory at 16 hpi (PubMed:33429879). Expressed in the late phase of the viral replicative cycle. Belongs to the NCLDV major capsid protein family.