Journal: JCI Insight
Article Title: IKK β is a β -catenin kinase that regulates mesenchymal stem cell differentiation
doi: 10.1172/jci.insight.96660
Figure Lengend Snippet: (A) The sequence of a conserved 6–amino acid motif found in β-catenin and IκB family members. (B) Immunoblotting for FLAG-tagged IKKβ and HA-tagged β-catenin proteins after immunoprecipitation using control IgG or antibodies against FLAG or HA proteins in C3H10T1/2 cells and HEK 293T cells. (C) In vitro phosphorylation of purified GST–β-catenin proteins by IKKβ in the presence of γ-[32P]ATP. (D–F) GST–β-catenin proteins phosphorylated by IKKβ in vitro were tryptic digested and analyzed by mass spectrometry. Figures show the recovered phosphorylated 30-residue fragment of β-catenin (residues 20–49). Tandem mass spectrum of the recovered peptide phosphorylated at ser45 residue (D). The peptides phosphorylated at ser33 and ser37 residues were coeluted. Color codes are used to mark fragment ions that allows distinguishing phosphorylation of ser33 (blue) and ser37 (red) (E). Tandem MS ion traces (10 ppm extraction) for the nonphosphorylated peptide, ser45- and ser33/ser37-phosphorylated peptides, and AUCs shown in italics (F).
Article Snippet: For cell-free kinase assay, 100 ng of recombinant human IKKβ proteins (SignalChem, I03-18G) were incubated with purified GST-tagged full-length human β-catenin protein and 150 nCi/nmol of γ-[ 32 P] ATP (PerkinElmer, BLU002A250UC) with a total 100 nM of ATP in kinase buffer (50 mM Tris-HCl, pH 7.7, 10 mM MgCl 2 , 1 mM DTT, and protease inhibitor cocktail).
Techniques: Sequencing, Western Blot, Immunoprecipitation, Control, In Vitro, Phospho-proteomics, Purification, Mass Spectrometry, Residue, Extraction