Analysis of Ethylene Receptor Interactions by Co-immunoprecipitation Assays.

Ethylene receptors are predominantly localized to the endoplasmic reticulum (ER) membrane, and coordinate ethylene signal output through protein-protein interactions with each other and additional signaling components. Here, we describe a co-immunoprecipitation (Co-IP) assay based on the use of the Tandem Affinity Purification (TAP) tag to examine the interactions of ethylene receptors in plant extracts. Human IgG-agarose beads are used to pull down TAP-tagged versions of the protein of interest from detergent extracts of Arabidopsis membranes, and the precipitate then is analyzed immunologically for co-purification of the ethylene receptors. This method has been successfully used to examine interactions of the receptors with each other as well as with the Raf-like kinase CTR1.