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

Antiserum directed against a C-terminal peptide of the human GLUT-3 (brain type) equilibrative glucose transporter isoform reacted with polypeptides M(r) 46,000-48,000 on immunoblots of human platelets. Photoirradiation 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-glucose, but not 440 mM L-glucose, consistent with glucose transporter function. 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.