A 'west-Western' blotting procedure indicates that adenovirus core protein V is linked to the capsid via protein VI. Double-labelling techniques employing confocal microscopy and immunofluorescence suggest that this linkage is disrupted following infection and penetration of the host cell. Protein V enters the nucleus presumably still in association with the other core proteins attached to the virus genome. Later in infection protein V rapidly accumulates in the nucleus in close association with nucleoli.