Stable association between the bovine papillomavirus E5 transforming protein and activated platelet-derived growth factor receptor in transformed mouse cells

Abstract

The 44-amino acid E5 transforming protein of bovine papillomavirus is the shortest protein known to induce tumorigenic transformation of fibroblasts. We showed previously that expression of the E5 protein activates the cellular β receptor for platelet-derived growth factor (PDGF) and proposed that the activated receptor transmits the transforming signal to the cell. Here we use coimmunoprecipitation analysis to show that the E5 protein and the activated PDGF receptor exist in a stable complex in transformed mouse C127 cells. These results suggest a distinct mechanism of growth factor receptor activation and provide further evidence that the PDGF receptor is an important target of the E5 protein.