N-Glycosylation influences human corticosteroid-binding globulin measurements

Objective Discrepancies in ELISA measurements of human corticosteroid-binding globulin (CBG) using detection monoclonal antibodies that recognize an epitope (9G12) within its reactive center loop (RCL), versus an epitope (12G2) in a different location, have suggested that CBG with a proteolytically cleaved RCL exists in blood samples. We have previously been unable to verify this biochemically, and sought to determine if N-glycosylation differences account for discrepancies in ELISA measurements of CBG.