Figure 3. Aurora B phosphorylated on S227/T232 has unique set of substrates including Borealin S165.

(a) A peptide array of known Aurora B substrates compared the phosphorylation of peptides by either doubly phosphorylated (WT) Aurora B to those phosphorylated by singly phosphorylated (S227A) Aurora B. Graph shows ratio of ATP incorporation into peptides phosphorylated by Aurora B WT and S227A recombinant protein. Data for all peptides analysed in Supplementary Data 2. (b) In vitro kinase assay to detect Borealin Ser165 phosphorylation by recombinant Aurora B(WT) or (S227A) protein. (c,d) DLD1 cells were induced to express GFP-Borealin WT or GFP-Borealin S165A for 16 h before analysis. (c) Representative confocal images of GFP-Borealin cells in each phase of mitosis and cytokinesis. Scale bar, 10 μm. (d) DLD1 cells induced to express GFP-Borealin were scored for the outcome of cytokinesis, successful cytokinesis resulting in two daughter cells or failed cytokinesis resulting in a binucleate cell. Graph is the mean (±s.e.m.) of three independent experiments where more than 100 cells per condition were scored. Two-way analysis of variance, **=P≤0.01.