Fig. (2) E2 proteins structure and interactions. HPV16 E2 threedimensional structure representing the three domains: Transactivation domain in the N-terminal part (TAD); Hinge unstructured domain in the centre, and DNA binding domain in the C-terminal part (DBD). A schematic representation of E2 is depicted below the 3D structure, with E2-interacting cellular proteins assigned to the interaction domain when it was determined.