Figure 1.

Labeling of insulin receptor subunits. IM-9 human lymphocytes were labeled either biosynthetically with [³⁵S]methionine or [³H]leucine, or externally with Na¹²⁵I and lactoperoxidase. The cells were then solubilized with Trion X-100, and glycoproteins were purified by chromatography with wheat germ agglutinin–agarose and then subjected to immunoprecipitation with control serum or serum containing antibodies to the insulin receptor (B-2). The immunoprecipitates were analyzed by SDS-PAGE after reduction with dithiothreitol, and the gel was then dried and subjected to autoradiography. Modified with permission from ref. 13.