Brain lysates were pre-cleared with protein A-Sepharose beads (YEASEN Biotech, Cat#36403ES25) and then incubated with primary antibody and protein A-coated Sepharose beads for 2 hr at 4 °C. Following three washes in lysis buffer, bound proteins were eluted from the beads in SDS sample buffer. For analysis by mass spectrometry, immunoprecipitates were first resolved by SDS-PAGE, with each lane cut into four slices for in-gel digestion. Tryptic peptides were analyzed by liquid chromatog-raphy-tandem mass spectrometry (LC-MS/MS, Thermo Orbitrap Fusion Lumos). Basing on the unique peptide numbers of proteins detected, we made the scatter plot of proteins bound to OLIG2.
