Functions of Co-Immunoprecipitation(Co-IP): （1）Detection of binding of two target proteins;（2）identification of identify a new binding partner of a particular protein; （3）getting the natural interacting protein complex by separation.
When the cells are lysed under non-denaturing conditions, interaction of protein-protein in intact cells is retained. If use the antibodies of protein x to have Immunoprecipitation
with x, protein Y which is bound to protein X also can precipitate. At present, refined protein A is used to bind to beads in argarose previously; after having an antibody reaction with solution containing antigens, protein A in beads can absorb antigens. This technique is usually used to detect binding of two target proteins and identify a new binding partner of a particular protein.