title: Detection of protein-protein interactions by coprecipitation.
abstract: Coprecipitation of proteins from whole-cell extracts is a valuable approach to testing for physical interactions between proteins of interest. When a precipitating antibody is used, this method is referred to as co-immunoprecipitation. Coprecipitation can be used to study interactions between known proteins and as a means of identifying components of a complex. This unit describes basic approaches to immunoprecipitating tagged proteins from whole-cell extracts. The extract is prepared under nondenaturing conditions, the protein of interest is precipitated, and the precipitate is tested for a second specifically associated protein. The approach can be used for native or epitope-tagged proteins for which antibodies are available, or for recombinant proteins that bind with high affinity to a molecule that can be coupled to a solid-phase matrix. An associated protein is detected by separating the precipitated proteins by SDS-PAGE and immunoblotting with a second antibody that recognizes the putative associated protein.
authors.affiliation: Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Elaine A
authors.initials: EA
authors.lastname: Elion
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D006801:Humans; D015151:Immunoblotting / Q000379:methods; D047468:Immunoprecipitation / Q000295:instrumentation / Q000379:methods*; D025941:Protein Interaction Mapping; D011506:Proteins / Q000378:metabolism*
chemical_list: D011506:Proteins