immortalizing function in rat embryo fibroblast cells

The E7 open reading frame of human papillomavirus type 16 (HPV-16) encodes a protein that can immortal-ize primary rat cells, cooperate with the ras oncopro-tein to transform low passage rat cells and transform established rodent cells to anchorage independence. The immortalizing and cooperation functions have been investigated using a series of point mutations that introduce single amino acid changes into the E7 protein in two distinct regions. Certain mutations altering amino acids conserved between the E7 protein of genital HPV types, the adenovirus Ela protein and simian virus 40 large T antigen abolished the ability of the E7 protein to immortalize or cooperate with ras in a focus forming assay. Mutations in a consensus sequence for a casein kinase II recognition site, which i