Co-localization of a glucose transporter and the insulin receptor in microsomes of insulin-treated rat adipocytes

Microsomal vesicles prepared from rat adipocytes were immuno-adsorbed to formaldehyde-fixed Staphylococcus aureus cells (Pansorbin) coated with anti-human-erythrocyte-glucose-transporter IgG. More than 75% of the glucose transporter detected was precipitated. The glucose transporter was about 10-fold enriched by the adsorption procedure. On insulin treatment, the insulin receptor in plasma membranes was internalized and the receptor in the microsome fraction increased 5-fold. Thirty-five % of the insulin receptor in the microsome fraction was recovered with the glucose-transporter-containing vesicles. These observations indicate that on insulin treatment a considerable portion of the microsome vesicles containing the insulin receptor fuses or becomes tightly associated with ones containing the glucose transporter.