UNIT 20.5 Detection of Protein-Protein Interactions by Coprecipitation

  1. Elaine A. Elion

Published Online: 1 MAY 2001

DOI: 10.1002/0471142727.mb2005s46

Current Protocols in Molecular Biology

Current Protocols in Molecular Biology

How to Cite

Elion, E. A. 2001. Detection of Protein-Protein Interactions by Coprecipitation. Current Protocols in Molecular Biology. 20:20.5.

Author Information

  1. Harvard Medical School, Boston, Massachusetts

Publication History

  1. Published Online: 1 MAY 2001
  2. Published Print: APR 1999

This is not the most recent version of the article. View current version (1 NOV 2006)


Coprecipitation of proteins from whole-cell extracts is a valuable approach to test for physical interactions between proteins of interest. This unit describes basic approaches to immunoprecipitating tagged proteins from whole-cell extracts. The approaches described can be adapted for other systems. In a typical experiment, as described here, cells are lysed and a whole-cell extract is prepared under nondenaturing conditions. The protein is precipitated from the lysate with a solid-phase affinity matrix and the precipitate is tested for the presence of 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 have been engineered to bind with high affinity to a molecule that can be coupled to a solid-phase matrix.