MSD SULFO-TAG labeled anti-phospho-tyrosine antibody detects phosphorylated tyrosine in native and denatured proteins. It is specific for phospho-tyrosine and does not react with either phospho-serine or phospho-threonine. This conjugated antibody may be used as a primary detection reagent to generate electrochemiluminescence in MESOSCALE DISCOVERY assays. It allows the user to detect analytes containing phosphorylated tyrosine residues.