title: Salvage of glucosylceramide by recycling after internalization along the pathway of receptor-mediated endocytosis.
abstract: To examine the (intra)cellular fate of a glycolipid, normally residing at the cell surface, a fluorescent analog of glucosylceramide, 6-[N-(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]hexanoylglucosylsp hingosine (C6-NBD-glucosylceramide), was inserted into the plasma membrane of baby hamster kidney cells at low temperature. Upon warming the cells to 37 degrees C, part of the glycolipid analog was internalized. A comparison with receptor-mediated uptake of transferrin revealed that after 2 min of warming, both C6-NBD-glucosylceramide and the transferrin-transferrin receptor complex are localized in the same intracellular compartment (early endosomes). We conclude that C6-NBD-glucosylceramide is internalized along the pathway of receptor-mediated endocytosis. When, after internalization of part of the membrane-inserted glycolipid analog, the residual pool of plasma membrane C6-NBD-lipid was removed by "back exchange" with a lipid acceptor, C6-NBD-glucosylceramide molecules can be shown to return intact to the plasma membrane. This demonstrates that glycolipids, analogous to a variety of protein receptors, are able to recycle to the plasma membrane after internalization.
authors.affiliation: Laboratory of Physiological Chemistry, State University Groningen, The Netherlands.
authors.forename: J W
authors.initials: JW
authors.lastname: Kok
authors.forename: S
authors.initials: S
authors.lastname: Eskelinen
authors.forename: K
authors.initials: K
authors.lastname: Hoekstra
authors.forename: D
authors.initials: D
authors.lastname: Hoekstra
mesh_terms: D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D002554:Cerebrosides / Q000378:metabolism*; D004705:Endocytosis; D005456:Fluorescent Dyes; D005963:Glucosylceramides / Q000378:metabolism*; D006028:Glycosphingolipids / Q000138:chemical synthesis; D008081:Liposomes; D008563:Membrane Lipids / Q000378:metabolism; D008858:Microscopy, Phase-Contrast; D014168:Transferrin / Q000378:metabolism
chemical_list: D002554:Cerebrosides; D005456:Fluorescent Dyes; D005963:Glucosylceramides; D006028:Glycosphingolipids; D008081:Liposomes; D008563:Membrane Lipids; D014168:Transferrin