FIGURE 2.

Survivin and Plk1 interact directly in vitro. In vitro pull-down assays. GST or GST-tagged versions of survivin (A) or GST-tagged versions of Plk1 (B) were incubated with in vitro translated (IVT) [³⁵S]methionine-labeled Plk1 (A), survivin (SVN), or the C-terminally truncated form of survivin, 1–90 (B). Plk1 interacted directly with GST-survivin and survivin truncations lacking the C-terminal α-helix. Conversely, survivin interacted with full-length Plk1, its kinase domain (KinD), and its PBD, which encompasses two Polo boxes (PB1 and PB2), and survivin 1–90 showed strongest interaction with GST-PBD. Note the reduced expression of full-length Plk1, probably due to decreased stability as indicated by the asterisk. Stick models of survivin and Plk1 are shown to illustrate the relevant domains (not drawn to scale). aa, amino acids.