Cellular proteins associated with the E5 oncoprotein of human papillomavirus type 16.

Human papillomavirus type 16 (HPV-16) is strongly implicated in the aetiology of premalignant and malignant disease of the cervix. The mechanisms by which HPV-16 induces cell transformation have been the subject of intense investigation for several years. The viral genome encodes three oncoproteins, E5, E6 and E7, but until recently only E6 and E7 were subjected to such scrutiny. The papillomaviruses exhibit strongly conserved genetic organisation [ 11 and the genes of bovine papillomavirus (BPV) have comparable counterparts in HPV-16. Much of our understanding of the action of HPV-16 E5 has come from studies of BPV E5. However, the properties of these analogous proteins do differ. BPV E5 is responsible for the major transforming activity of the virus whereas the major transforming activity of HPV-16 occurs through the action of the E6 and E7 proteins [2,