Distinct Domains of Simian Virus 40 Large T Antigen Mediate Its Association with Different Cellular Targets

The large tumor antigen encoded by simian virus 40 (SV40 large T) is a multifunctional protein. During SV40 lytic infections it is required for several steps of viral replication. Furthermore, large T is able to fully transform primary cells, i.e. it can mediate both transforming functions defined so far, immortalization of cells and expression of the transformed phenotype, (reviewed in (1)). The multitude of functions performed by large T requires a complex regulation of its activities in the cell. This may, in part, be achieved by the various posttranslational modifications described for large T, like phosphorylation (2), ADP-ribosylation (3), glycosylation (4), and fatty acid acylation (5). In addition, oligomerization of large T and complex formation with the cellular protein p53 might be involved in modulating its activities (reviewed in (6)).