Hexon protein is a major coat protein of adenoviruses. Adenoviruses capsids have three principal protein components: the hexon, the penton, and the fiber. Hexon consists of three subunits together forming two major components of different morphological symmetry. A triangular top with three towers of density is superimposed on a more bulky pseudo hexagonal base. The symmetry of the top is in accord with the trimeric nature of hexon, but that of the base derives from the molecular function, which is to provide a densely packed impenetrable protective outer layer for the virion.