UNIT 20.5 Detection of Protein-Protein Interactions by Coprecipitation

  1. Elaine A. Elion

Published Online: 1 NOV 2006

DOI: 10.1002/0471142727.mb2005s76

Current Protocols in Molecular Biology

Current Protocols in Molecular Biology

How to Cite

Elion, E. A. 2006. Detection of Protein-Protein Interactions by Coprecipitation. Current Protocols in Molecular Biology. 76:20.5:20.5.1–20.5.10.

Author Information

  1. Harvard Medical School, Boston, Massachusetts

Publication History

  1. Published Online: 1 NOV 2006
  2. Published Print: OCT 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.