[42] Biosynthetic, Surface Labeling, and Isolation of Membrane Immunoglobulin

This chapter reviews the cell surface iodination, which is a powerful tool for the study of cell surface immunoglobulins (Ig). The surface Ig status of viable cells can be determined. Molecules which are present in low numbers or have a slow biosynthetic rate can be studied biochemically and the effect of various agents which change the surface Ig phenotype can also be monitored. The chapter explores that number of methods for cell surface labeling has been reported. The most popular is lactoperoxidase-catalyzed iodination using H2O2 directly or H2O2 generated by the glucose–oxidase system. If properly used, this procedure achieves the vectorial labeling of membrane but not cytoplasmic proteins and is not toxic to cells. It also discusses that the choloramine-T method utilizes a powerful oxidant followed by strong reducing conditions to terminate the reaction and is often deleterious to cells.