Thrombin-induced translocation of GLUT3 glucose transporters in human platelets (original) (raw)
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Journal of Cell Biology, 1997
Increased energy metabolism in the circulating blood platelet plays an essential role in platelet plug formation and clot retraction. This increased energy consumption is mainly due to enhanced anaerobic consumption of glucose via the glycolytic pathway. The aim of the present study was to determine the role of glucose transport as a potential rate-limiting step for human platelet glucose metabolism. We measured in isolated platelet preparations the effect of thrombin and ADP activation, on glucose transport (2-deoxyglucose uptake), and the cellular distribution of the platelet glucose transporter (GLUT), GLUT-3. Thrombin (0.5 U/ml) caused a pronounced shape change and secretion of most α-granules within 10 min. During that time glucose transport increased approximately threefold, concomitant with a similar increase in expression of GLUT-3 on the plasma membrane as observed by immunocytochemistry. A major shift in GLUT-3 labeling was observed from the α-granule membranes in resting ...
GLUT-3 (brain-type) glucose transporter polypeptides in human blood platelets
Thrombosis Research, 1995
Antiserum directed against a C-terminal peptide of the human GLUT-3 (brain type) equilibrative glucose transporter isoform reacted with polypeptides Mr 46,000-48,000 on immunoblots of human platelets. Photoirradiation of human platelets in the presence of 3H-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-l (erythrocyte type) glucose transporter polypeptides were detected, and there was no evidence of GLUT-2 (liver type) transporter on immunoblots of platelet proteins. Human blood platelets rapidly metabolize many monosaccharides i?z vitro [ 1,2], and it is probable that plasma D-glucose is an important source of metabolic energy for platelets in viva. Addition of some monosaccharides increased spontaneous platelet aggregation of whole blood it? vitro [21], and there is evidence of hyperreactivity of platelets in patients suffering from diabetes mellitus [ 181. However, the pathway(s) for monosaccharide entry into human platelets has yet to be thoroughly characterized. Uptake measurements suggest that D-glucose, and other physiologically important monosaccharides, enter platelets through an equilibrative facilitated diffusion pathway(s). Light scattering changes observed when suspensions of platelets were exposed to isotonic concentrations of monosaccharides indicated that some hexose sugars, including glucose and fructose, enter platelets through a phloridzin-sensitive equilibrative