Protein extraction, MBP-pulldown, and co-immunoprecipitation assays

Total, cytoplasmic, and nuclear protein extractions were performed using a protein extraction kit (CWBIO, Beijing, China). The protein concentrations were determined using a BCA protein assay kit (Pierce Biotechnology, Rockford, IL, USA). One milligram of total protein from each sample was used for MBP-pulldown or co-immunoprecipitation assays following protocols reported previously³⁴. A description of the antibodies used is provided in the Supplementary Information. Immunoblotting bands were subjected to gray-scale quantification using ImageJ software.