Magnet-assisted immunoprecipitation (MAIP) of recombinant protein v1

This protocol describes a magnet-assisted immunoprecipitation (MAIP) workflow for the isolation of a TGF-β1/PD-L1 fusion protein from mammalian cell lysates under native conditions. Dynabeads M-280 Tosylactivated are covalently coupled with either anti-TGF-β1 or anti-PD-L1 antibodies to enable selective capture of the fusion protein following transient expression in HEK 293 cells. The method includes detailed steps for antibody coupling, protein extraction, immune-magnetic isolation, acidic elution, and neutralization, allowing recovery of intact protein suitable for downstream biochemical analyses such as SDS-PAGE and immunoblotting.