Cells were lysed in triple detergent lysis buffer (Thermo Fisher Scientific) and then incubated with antibody-conjugated agarose beads at 4 °C overnight, or with unconjugated antibody for 2 h followed by overnight incubation with protein A/G-agarose beads (Beyotime Biotechnology). After three washes with lysis buffer, proteins were heat-denatured in 2x SDS sample buffer, then separated by 8−15% polyacrylamide by SDS-PAGE and transferred to Immobilon-FL Membrane (Millipore). Membranes were probed with primary antibodies as listed in Supplementary Table S3, then incubated with LICOR IRDye secondary antibodies diluted 1:20,000. Immune complexes were visualised and quantified with the Odyssey Imaging System (LI-COR, USA) or incubated with a peroxidase-conjugated secondary antibody and detected by enhanced chemiluminescence (Beyotime Biotechnology). Full blots of images cropped for presentation are presented in Supplementary Fig. 8.
