GLUT-3 (BRAIN-TYPE) GLUCOSE-TRANSPORTER POLYPEPTIDES IN HUMAN BLOOD-PLATELETS

Antiserum directed against a C-terminal peptide of the human GLUT-3 (b rain type) equilibrative glucose transporter isoform reacted with poly peptides M(r) 46,000-48,000 on immunoblots of human platelets. Photoir radiation of human platelets in the presence of H-3-cytochalasin B led to radiolabeling of polypeptides of identical mobility. This labeling was substantially reduced by preincubation the cells with 440 mM D-gl ucose, but not 440 mM L-glucose, consistent with glucose transporter f unction. Only traces of GLUT-1 (erythrocyte type) glucose transporter polypeptides were detected, and there was no evidence of GLUT-2 (liver type) transporter on immunoblots of platelet proteins.