%0 Journal Article %A Messerschmitt, A. %A Disela, C. %A Dilworth, S. %A Marti, A. G. %A Ballmer-Hofer, K. %T Polyomavirus middle-T antigen lacking a membrane anchor sequence accumulates in the nucleus %D 1996 %J Journal of General Virology, %V 77 %N 1 %P 17-26 %@ 1465-2099 %R https://doi.org/10.1099/0022-1317-77-1-17 %I Microbiology Society, %X Three proteins expressed early in the replicative cycle of polyomavirus also play an essential role during virus-mediated tumorigenesis. One of the proteins, middle-T antigen, has been shown to bind cellular proteins involved in cell signalling such as c-Src, phosphatase 2A, phosphatidylinositol 3-kinase and SHC. Association of middle-T antigen with cellular membranes has been shown to be essential for middle-T-mediated cell transformation. A mutant virus encoding a truncated form of middle-T lacking a carboxy-terminal hydrophobic sequence mediating membrane association is not oncogenic. This mutant middle-T still binds phosphatase 2A through amino-terminal sequences common to small-and middle-T and is localized in the nucleus, although the protein does not contain a classical nuclear targeting sequence. Mutations introduced into the amino-terminal domain affecting the ability of truncated middle-T to bind phosphatase 2A prevented accumulation of the protein in the nucleus and led to localization in the cytoplasm. This suggests that nuclear localization of truncated middle-T may be a consequence of binding to phosphatase 2A. %U https://www.microbiologyresearch.org/content/journal/jgv/10.1099/0022-1317-77-1-17