Co-IP Bait and Prey, & More Applications of Immunoprecipitation (IP) | CST Tech Tips

Learn the fundamental definitions of bait and prey proteins in co-immunoprecipitation experiments. The bait protein is used to capture the prey protein, which binds directly or indirectly to the bait.

Choose between two co-IP strategies based on your research question: using the target protein as prey with a known binding partner as bait, or vice versa. Select a validated antibody against the bait protein for immunoprecipitation.

Execute the co-immunoprecipitation assay and identify prey proteins through Western blotting or other analytical methods. Consider protein structure during experimental design to avoid interference with antibody binding.

If weak or absent bands appear in Western blot analysis, use IP antibodies targeting different epitopes on the target protein to increase signal. This approach can improve detection sensitivity.

Perform a reciprocal co-immunoprecipitation by switching the bait and prey proteins to confirm positive results. This validation step increases confidence in protein-protein interaction findings.

Use chromatin immunoprecipitation to investigate protein-DNA interactions by immunoprecipitating proteins suspected to bind DNA, followed by sequencing or PCR analysis. This technique involves more operational steps than standard co-IP.

Use specialized motif antibodies to enrich signal proteins with phosphorylation or post-translational modifications, then identify them using mass spectrometry. This approach investigates how signaling activity changes with treatment.