It has two independent nuclear localization signals. Large T is a DNA binding protein that oligomerizes using a zinc finger. In the N-terminus large T binds tumor suppressors of the Rb family. It also binds hsc 70 through its J domain. Phosphorylation of large T at the end of the C-terminal domain can regulate its activity in DNA replication.
Large T is a protein with multiple functions.
These are related on the one hand to its role as an initiator of viral DNA replication and on the other to its ability to promote cell cycle progression. The protein is capable of blocking differentiation of cells, of making embryo cells immortal, and of inducing programmed cell death. The C-terminal domain is sufficient for initiation of viral DNA replication is the cellular environment is right, that is the cell cycle is progressing. The N-terminal domain is involved in regulating cell cycle progression. Much of LT function associated with cell cycle depend on its interaction with members of the Rb tumor suppressor family.