Identification and partial purification of the insulin-responsive glucose transporter from 3T3-L1 adipocytes

The glucose transporter in 3T3-L1 adipocytes has been identified as a polypeptide of average Mr 51000 by means of its reaction with antibodies raised against the purified human erythrocyte glucose transporter and by photolabeling with [3H]cytochalasin B. The finding that the antibodies immunoprecipitated the photolabeled polypeptide demonstrated that both methods detected the same polypeptide. The 3T3-L1 adipocyte glucose transporter has been partially purified. The main steps in the purification procedure were the preparation of salt-washed cellular membranes, Triton X-100 solubilization, and immunoaffinity chromatography on affinity-purified antibodies against the human erythrocyte transporter. A simple method of affinity purification of these antibodies, which consists of adsorption from serum onto protein-depleted erythrocyte membranes and release with acid, and an assay for the 3T3-L1 adipocyte transporter polypeptide, which employs immunoblotting, have been developed.