What is the difference between immunoprecipitation and coimmunoprecipitation?

Immunoprecipitation (IP) targets the primary protein that binds the antibody. It is used to isolate proteins and other biomolecules from cell or tissue lysates for the subsequent Western blot detection.

The Co-Immunoprecipitation assay (Co-IP) is based on the same methodology as immunoprecipitation. In co-immunoprecipitation (Co-IP), an antibody is used to purify its target antigen, along with its binding partners, from a mixed sample. In this case, the antigen is the bait protein and its binding partners are the prey proteins that are co-purified by the antibody:antigen interaction. It is the most widely used in vitro method of investigating protein-protein interactions.