Patent ID: 7846746

Claim:
A method for determining binding of a selected protein-protein interaction domain to a complementary binding partner of said selected protein-protein interaction domain present on a protein obtained from a biological specimen comprising: (a) obtaining a protein mixture from the biological specimen; (b) immobilizing the proteins of said protein mixture to a solid support; (c) contacting the immobilized proteins with a plurality of different unlabeled protein-protein interaction domains under appropriate binding conditions, wherein the different unlabeled protein-protein interaction domains are contacted with the immobilized proteins in the same binding reaction; (d) simultaneously with or subsequent to step (c) contacting the immobilized proteins with at least one labeled selected protein-protein interaction domain, under appropriate binding conditions, wherein the label is selected from the group consisting of biotinylation sequences, antibody recognition sequences, glutathione-S-transferase tags, oligonucleotides, glutathione conjugates, fluorophores, and combinations thereof, the labeled protein-protein interaction domain being different from the unlabeled protein-protein interaction domains wherein the protein-protein interaction domains compete for binding to the immobilized proteins; (e) washing away unbound labeled protein-protein interaction domain; and (f) detecting the binding of the labeled protein-protein interaction domain to a complementary binding partner of said selected protein-protein interaction domain wherein detection of said binding indicates the presence of a protein containing the complementary binding partner of said selected protein-protein interaction domain in said biological specimen.