Biotinylation: an alternative to radioiodination for the identification of cell surface antigens in immunoprecipitates.

A method has been developed in which the conventional radioiodine label is replaced by non-radioactive biotin in studies involving the immunoprecipitation and analysis of cell surface antigens. The labelling reagent, d-biotinyl-N-hydroxysulfosuccinimide ester (NHSS-biotin), reacts preferentially with lysine residues in polypeptides and possibly also with free amino-groups on carbohydrates and lipids. The reagent can be used as a cell surface label, does not interfere with antigen-antibody interactions and allows labelled molecules to be detected with high sensitivity using streptavidin-peroxidase conjugates. The target antigens of a range of monoclonal antibodies to human cell surface components have been identified using this procedure.