In-vivo Cross-linking of Biotinylated Peptide Ligands to Cell Surface Receptors

In-vivo cross-linking of biotinylated peptides is a technique to analyze the interaction of small proteins or peptide ligands with their corresponding receptors. Here, we describe an in-vivo method in which leaves of living plants, transiently expressing receptor proteins, are infiltrated with biotinylated peptides. The interaction between ligand and receptor is irreversibly fixed by the infiltration of a cross-linking agent. Subsequently, co-immunoprecipitation is used to pull down the receptor-ligand pair. After western blotting, the biotin tag of the ligand peptide cross-linked to the receptor can be detected by streptavidin-AP conjugate on the membrane.