Compositions and methods for labeling and detecting binding partners

A method of detecting a binding partner of a molecule of interest comprising

• a) adding a labeling composition and a target composition to a sample,
• wherein the labeling composition comprises a ligandable tag conjugated to a labeling enzyme,
• wherein the target composition comprises a ligand and a molecule of interest,
• wherein the ligand of the target composition is a ligand for the ligandable tag of the labeling composition;
• b) incubating the labeling composition and target composition with the sample under conditions that allow the molecule of interest to bind to a binding partner in the sample, wherein when the molecule of interest binds to a binding partner in the sample, the labeling enzyme labels the binding partner,
• c) detecting the presence of the label in the sample,
• wherein the presence of a label is indicative of a binding partner of a molecule of interest present in the sample.

A method of identifying a binding partner of a molecule of interest comprising

• a) adding a labeling composition and a targeting composition to a sample,
• wherein the labeling composition comprises a ligandable tag, a linker, and a labeling enzyme, wherein the linker attaches the ligandable tag to the labeling enzyme,
• wherein the targeting composition comprises a ligand conjugated to a molecule of interest,
• wherein the ligand of the targeting composition is a ligand for the ligandable tag of the labeling composition;
• b) incubating the labeling composition and targeting composition with the sample under conditions that allow the molecule of interest to bind to a binding partner in the sample, wherein when the molecule of interest binds to a binding partner in the sample, wherein the labeling enzyme labels the binding partner;
• c) detecting the presence of the label in the sample, and
• d) identifying the labeled binding partner.