The major capsid protein of the adenovirus strain is also known as a hexon. Structural domains comprising this superfamily share the structure of the minor capsid proteins IIIa, thought to be involved in vertex stabilisation and genome packaging. It stabilises vertices by tethering the penton bases to neighbouring peripentonal hexons, and lashes peripentonal hexons to the neighbouring hexons through its interaction with hexon-linking protein. During virus assembly, it plays a role in genome packing through its interaction with packaging protein 3 PMID:21632753,PMID:20798312.