Co-Immunoprecipitation (Co-IP) is a powerful method used to study protein/protein interactions. In Co-IP, one antibody is used to immunoprecipitate a target antigen and also co-precipitate any bound interacting proteins within a sample. This complex is then detected by Western blot using a second antibody targeted against one of the bound interacting proteins.
Active Motif offers 2 kits for Co-IP. The original Nuclear Complex Co-IP Kit was designed to optimize Co-IP of nuclear complexes; it provides an optimized nuclear extraction method that preserves nuclear protein complexes.
The new Universal Magnetic Co-IP Kit is an improved version of the Nuclear Complex Co-IP Kit. In addition to optimizing Co-IP of nuclear protein complexes, the kit contains reagents for performing Co-IP of cytoplasmic protein complexes. The greatest benefit, however, comes from the inclusion of protein G-coated magnetic beads, which speed and simplify the procedure while greatly reducing background. This makes it possible to use low-stringency buffers that better maintain protein complexes.