Identification of the human papilloma virus-1a E4 gene products.

Abstract

Antibodies prepared against a human papilloma virus‐1 (HPV‐1) E4/beta‐galactosidase fusion protein identified several polypeptides in HPV‐1, but not HPV‐2 or 4, induced papillomas. The major E4 protein, that represented up to 30% of total cellular protein, was a 16/17‐K doublet which was purified by column chromatography and analysed for amino acid content. A peptide derived by chymotryptic digestion was purified by h.p.l.c. and subjected to amino acid sequencing. The unique sequence obtained, Gly‐His‐Pro‐Asp‐Leu‐Ser‐Leu, identified the 16/17‐K doublet as a product of the HPV‐1 E4 gene region. Antibodies to both the E4/beta‐galactosidase fusion protein and the 16/17‐K doublet identified two smaller polypeptides (10/11‐K) which may represent spliced products of E4. We propose that the products of the HPV‐1 E4 gene region are not classical DNA tumor virus early proteins and suggest that they play a role in virus maturation.