FIGURE 6.25 Interactions of polyoma middle T antigen with membrane proteins to initiate cellular transformation. Phosphatidylinositol-3 kinase (PI3K) and c-src are localized in the plasma membrane. The src kinase phosphorylates middle T on a tyrosine residue (Y). This generates binding sites for a variety of other cellular signaling proteins such as PI3K. The resultant complex closely resembles an activated growth factor receptor bound to signal transduction proteins. Serine residues (S) on middle T that are phosphorylated by other protein kinases are also indicated. [Drawn from data in DiMaio et al. (1998).]
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