Major capsid protein that self-associates to form 240 hexon trimers, each in the shape of a hexagon, building most of the pseudo T=25 capsid. Assembled into trimeric units with the help of the chaperone shutoff protein. Transported by pre-protein VI to the nucleus where it associates with other structural proteins to form an empty capsid. Might be involved, through its interaction with host dyneins, in the intracellular microtubule-dependent transport of incoming viral capsid to the nucleus. Homotrimer. Interacts with the capsid vertex protein; this interaction binds the peripentonal hexons to the neighboring penton base. Interacts with the hexon-linking protein; this interaction tethers the hexons surrounding the penton to those situated in the central plate of the facet. Interacts with the hexon-interlacing protein; this interaction lashes the hexons together. Interacts with host dyneins DYNC1LI1 and DYNC1I2; this interaction might be involved in intracellular microtubule-dependent transport of incoming viral capsid. Interacts with the shutoff protein; this interaction allows folding and formation of hexons trimers. Interacts with pre-protein VI; this interaction probably allows nuclear import of hexon trimers and possibly pre-capsid assembly. Forms the capsid icosahedric shell. Present in 720 copies per virion, assembled in 240 trimers. Expressed in the late phase of the viral replicative cycle. All late proteins expressed from the major late promoter are produced by alternative splicing and alternative polyadenylation of the same gene giving rise to non-overlapping ORFs. A leader sequence is present in the N-terminus of all these mRNAs and is recognized by the viral shutoff protein to provide expression although conventional translation via ribosome scanning from the cap has been shut off in the host cell. Belongs to the adenoviridae hexon protein family.