UNIT 5.25 Detection of Protein-Protein Interactions by Coprecipitation

  1. Elaine A. Elion

Published Online: 1 MAY 2006

DOI: 10.1002/0471142301.ns0525s35

Current Protocols in Neuroscience

Current Protocols in Neuroscience

How to Cite

Elion, E. A. 2006. Detection of Protein-Protein Interactions by Coprecipitation. Current Protocols in Neuroscience. 35:5.25:5.25.1–5.25.10.

Author Information

  1. Harvard Medical School, Boston, Massachusetts

Publication History

  1. Published Online: 1 MAY 2006
  2. Published Print: APR 2006


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.


  • co-immunoprecipitation;
  • immunoprecipitation;
  • protein interactions;
  • protein tags;
  • antibody;
  • immunoblot