FIGURE 2.

Rb domain requirements for inhibition of E2F^TD. A, ITC titration curves show that E2F^TD binds to enzymatically dephosphorylated Rb^55–928 (Rb^55–928; K_d = 0.04 ± 0.02 μm) with a similar affinity as to the unphosphorylated Rb pocket domain (dephosRb^380–787; K_d = 0.045 ± 0.007 μm). Phosphorylation of Rb^55–928 results in a weaker affinity (phosRb^55–928; K_d = 11 ± 3 μm). B, E2F^TD dissociation constants were measured by ITC for binding to truncation mutants of Rb. The data demonstrate that RbN is required for phosphorylation-induced inhibition of E2F^TD.