A Powerful Method for Studying Protein–Protein Interactions in Plants: Coimmunoprecipitation (Co-IP) Assay

With the continuous application of molecular biology technologies in the field of plant virology, growing evidence shows that the interactions between viral proteins or virus and host are essential in almost all steps of virus infection. Various methods used to study protein-protein interactions have been extensively adapted for plant virology research. Among them, coimmunoprecipitation (Co-IP) is considered as a standard and powerful tool by molecular biologists to analyze the occurrence of protein-protein interactions in living cells. This method can help us gain a deeper understanding of the functions of target proteins, which interact with other proteins or belong to some functional complexes. In this chapter, we detail a protocol for the Co-IP assay and highlight challenges associated with this method.