FIG 3.

Diubiquitin synthesis assay demonstrating that ubiquitin chains generated by D143K Ube2R2 and R54D ubiquitin are predominantly linked through Lys 48. Time course data show that reaction mixtures containing K48R/R54D acceptor ubiquitin and WT or D143K Ube2R2 resulted in similar amounts of product formation, whereas the reaction mixture containing R54D acceptor ubiquitin and D143K Ube2R2 resulted in far greater product formation than the reaction mixture containing WT Ube2R2 and R54D ubiquitin. The acceptor ubiquitin concentration was 100 μM.