L-fucose is accumulated via a specific transport system in eukaryotic cells.
L-Fucose is a monosaccharide normally present at low concentrations in serum and is the only levorotatory sugar utilized by mammalian systems. The metabolism of L-fucose is only partially understood. In this report, we characterize the uptake of L-fucose by four widely varying mammalian cell lines (murine neuroblastoma, bovine aortic endothelial, murine cerebral microvessel endothelial, and Madin-Darby canine kidney cells). Based on the criteria of saturability and specificity of L-fucose uptake, we conclude that L-fucose is accumulated via a specific recognition mechanism. Accumulation of L-fucose at 4 degrees C and in the presence of colchicine and cytochalasin D rules out receptor-mediated endocytosis as an uptake mechanism. Thus, the accumulation appears to be via a carrier system. Using a variety of criteria, we determined that L-fucose is not taken up by a glucose transporter system. Accumulation of L-[5,6-3H]fucose is Na(+)-independent and reduced by loading cells with L-fucose or depleting the cell of its phosphorylation capability, suggesting that the uptake of L-fucose is by passive facilitative diffusion. A significant amount of the L-fucose taken up by each of the four cell types was incorporated into protein and secreted into the medium.
Wiese
T J
TJ
Department of Internal Medicine, University of Iowa, Iowa City 52246.
Dunlap
J A
JA
Yorek
M A
MA
D000818:Animals; D001011:Aorta; D001692:Biological Transport / Q000187:drug effects; D002417:Cattle; D002460:Cell Line; D002478:Cells, Cultured; D002560:Cerebrovascular Circulation; D003571:Cytochalasin B / Q000494:pharmacology; D003847:Deoxyglucose / Q000378:metabolism; D004058:Diffusion; D004285:Dogs; D004730:Endothelium, Vascular / Q000378:metabolism*; D005643:Fucose / Q000378:metabolism*; D007668:Kidney; D007700:Kinetics; D051379:Mice; D008833:Microcirculation; D009005:Monosaccharides / Q000494:pharmacology*; D009447:Neuroblastoma; D010693:Phloretin / Q000494:pharmacology; D010695:Phlorhizin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D009005:Monosaccharides; D005643:Fucose; D003571:Cytochalasin B; D003847:Deoxyglucose; D010695:Phlorhizin; D010693:Phloretin