Journal of Comprehensible Results

Co-immunoprecipitation can be used to determine the levels of protein complexes. Co-immunoprecipitation uses a column filled with agarose beads that have an antibody attached to them. These antibodies will attach to both their individual protein of interest as well as complexes involving their protein of interest. After antibody capture occurs, the solution is centrifuged so that the heavy antibody-protein complexes form a pellet. Then the pellet is subjected to western blotting or another staining method. When this western blot is performed, a primary antibody that targets the second half of the complex is used.

The basic steps of coimmunoprecipitation are outlined above[13].

For example, if you wanted to measure the levels of MAG-Fyn complexes you would use an anti-MAG antibody to initially select for MAG and anything attached to MAG. Then anything not bound to the anti-MAG antibodies would be removed. Finally, the remaining contents would by subjected to a western blot that uses an anti-Fyn antibody as the primary antibody; this ensures that only MAG-Fyn complexes are being selected and not either component on its own. A western blot is performed as described here:Western Blot