Figure 5.

Role of the N-terminus of Ring1a and Ring1b. (A) Assays performed with isolated Ring1a_30–111 and Bmi1 and complexes of Ring1b/Bmi1, Ring1b_16–114/Bmi1₁₀₉ and Ring1a₁₁₁/Bmi1₁₀₉ using conditions as described in the legend of Figure 1 and Materials and methods; Western blot against ubiquitin. (B) Bmi1 was titrated to the indicated final concentration into 2 μM Ring1a_30–111, E1, MgATP, UbcH5c and nucleosomes; Western blot against ubiquitin. (C) Titration of Bmi1 to the indicated final concentrations into 2 μM Ring1a_30–111 or Ring1a₁₁₁/Bmi1₁₀₉, respectively, using the same conditions as described in (B); Western blot against ubiquitin.