Figure 6. CDK1‐driven T172 phosphorylation stabilises BCL9 and regulates its interaction with clathrin.

1. Venn diagram analysis of BCL9 mitotic phosphorylation sites in HeLa cells by mass spectrometry.
2. Schematic diagram of the position of two phosphorylation sites on the BCL9 N‐terminal domain, and protein alignment analysis of the sequence around T172 in different species from http://www.uniprot.org.
3. In vitro CDK1/cyclin B1 kinase assay for immunoprecipitation‐purified BCL9‐Flag or T172A‐Flag proteins.
4. Immunoprecipitation analysis of transiently expressed BCL9‐MF or T172A‐MF interactors in synchronised cells, from G1S to G2M phase. The relative level of BCL9‐MF or T172A‐MF immunoprecipitation is determined; red numbers indicate up‐regulation; and green numbers indicate down‐regulation compared to the starting time point.
5. Immunoprecipitation analysis of the transiently expressed BCL9‐MF interaction in mitotic cells treated with RO3306.
6. Immunoprecipitation analysis of the interaction of the T172 inactive mutant T172A, the activation mutant T172D, and the double inactive mutant T172/T144 (2A) or activation mutant (2D) transiently expressed in mitotic cells.
7. Quantification for the inactive or activation mutant interactions indicated in Fig 6F. The wild‐type BCL9 interaction is normalised to 1, indicated by a green dashed line with an arrow.
8. A schematic diagram of BCL9 phosphorylation regulation of its interactions.

Data information: See also Fig EV6.Source data are available online for this figure.