Co-Immunoprecipitation-Blotting: Analysis of Protein-Protein Interactions

Immunoprecipitation of protein complexes, also known as co-immunoprecipitation (Co-IP), is a powerful technique to analyze protein-protein interactions. Commercial availability of Dynabeads^® Protein A magnetic beads provides a fast, convenient, and efficient method for protein interaction studies by Co-IP followed by immunoblotting (Co-IP-blotting). Recently, the Co-IP-blotting technique helped us to investigate complicated protein interactions/networks involving nuclear protein 1 (Nupr1), a recently discovered regulator of apoptosis in human cartilage cells. The methods and protocols for Co-IP-blotting are reported here in detail.