A "hanging" coverslip method for cell surface iodination of monolayer cultures

A procedure is described by which the use of a 1,3,4,6-tetrachloro-3 alpha,6 alpha-diphenyl glycoluril (iodogen)-coated coverslip to iodinate the cell surface proteins of monolayer cultures has been improved by "hanging" the coverslip at a defined distance from the cells. This method allows gentle manipulation of the cell culture, resulting in retention of high cell viability and in recovery of the cell monolayer with a minimum of mechanical damage. In addition, it allows the safe disposal of the radioactive coverslip upon completion of the reaction. Finally, the labeling is surface specific. The application of this procedure to 3T3 fibroblasts results in labeling of proteins comparable to lactoperoxidase-catalyzed iodinations.