The HPV E7 proteins are small (HPV16 E7 comprising 98 amino acids, 15kDa), zinc binding phosphoproteins which are localised in the nucleus. They are structurally and functionally similar to the E1A protein of subgenus C adenoviruses. The first 16 amino-terminal amino acids of HPV16 E7 contain a region homologous to a segment of the conserved region 1 (CR1) of the E1A protein of subgenus C adenoviruses. The next domain, up to amino acid 37, is homologous to the entire region 2 (CR2) of E1A. Genetic studies have established that these domains are required for cell transformation in vitro, suggesting similarities in the mechanism of transformation by these viruses. The CR2 homology region contains the LXCXE motif (residues 22-26) involved in binding to the tumour suppressor protein pRb.
HPV 16-E7; HPV16E7