Wash 2X the beads with 1 ml of PBS + 5mg/ml of BSA.
Add the antibody (according to the suppliers instruction) to the beads in 500 μl of PBS + 5mg/ml of BSA and incubate 1h30 under agitation at 4°C.
Wash the beads with 1ml of PBS + 5mg/ml of BSA and ressuspend them in lysis buffer + PIC.
Add a minimum of 500 μg of protein extract and incubate 2h to ON at 4°C under agitation.
Wash 3 times with lysis buffer + PIC (supplemented or not with salt)
Ressuspend in laemmly buffer 1X and proceed with SDS-PAGE and western blot.