FIG. 3.

Examples of key results from the secondary MS screen. (A) Representation of the FOXO3-CDK4 interaction as observed in the gel-based MS/MS experiment. CDK4 binds preferably to FOXO3-Cys622 and migrates at an apparent MW that represents a covalent complex. (B) Similar representations for nuclear import receptors that were identified to bind to FOXO3. Low amounts of TNPO1 were found, whereas substantial amounts of IPO7 and IPO8 were found to bind specifically to Cys150. See also Supplementary Figure S5 for a similar analysis of TNPO1, IPO7, and IPO8 binding to FOXO4.