Biochemical purification of native immune protein complexes.

Protein complex purification represents a powerful approach to identify novel players in plant innate immunity. However, the identification of interacting protein partners within a natural context has been a challenge for researchers. In this chapter, we describe a method of immunoaffinity chromatography using purified, antibodies to isolate native protein complexes from wild-type tissue. We detail the antibody purification and immobilization steps in addition to the co-immunoprecipitation protocol. In addition, a method to prepare protein samples for mass spectroscopy analysis is described. This straightforward protocol has been used to isolate and identify novel components of Arabidopsis immunity-associated protein complexes.