title: Lactosylceramide is synthesized in the lumen of the Golgi apparatus.
abstract: Recently, synthesis of lactosylceramide has been described to occur on the cytosolic face of the Golgi [(1991) J. Biol. Chem. 266, 20907-20912]. The reactions following in the biosynthesis of higher glycosphingolipids are known to take place in the lumen of the Golgi. For our understanding of the functional organization of the multiglycosyltransferase system of glycosphingolipid synthesis in the Golgi, the knowledge of the topology of individual reactions is a prerequisite. We have developed a simple and quick assay system for sphingolipid biosynthesis and have obtained evidence that lactosylceramide is synthesized in the lumen of the Golgi. Because lactosylceramide is generated by galactosylation of glucosylceramide which, in turn, is synthesized from ceramide and UDP-Glc on the cytosolic surface of the Golgi apparatus, further efforts will be directed to the characterization of a glucosylceramide-translator in the Golgi membranes rather than a lactosylceramide-translocator.
authors.affiliation: Institut für Biochemie, Universität Heidelberg, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Lannert
authors.forename: C
authors.initials: C
authors.lastname: Bünning
authors.forename: D
authors.initials: D
authors.lastname: Jeckel
authors.forename: F T
authors.initials: FT
authors.lastname: Wieland
mesh_terms: D000818:Animals; D015703:Antigens, CD; D016466:CHO Cells; D006224:Cricetinae; D005700:Galactosyltransferases / Q000378:metabolism; D005963:Glucosylceramides / Q000378:metabolism; D005964:Glucosyltransferases / Q000378:metabolism; D006028:Glycosphingolipids / Q000096:biosynthesis*; D006056:Golgi Apparatus / Q000378:metabolism*; D007790:Lactosylceramides; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013696:Temperature; D017855:Transferases (Other Substituted Phosphate Groups) / Q000378:metabolism; D014531:Uridine Diphosphate Galactose / Q000378:metabolism
chemical_list: D015703:Antigens, CD; D005963:Glucosylceramides; D006028:Glycosphingolipids; D007790:Lactosylceramides; D014531:Uridine Diphosphate Galactose; C009744:CDw17 antigen; D005700:Galactosyltransferases; D005964:Glucosyltransferases; C039090:UDPgalactose-glucosylceramide galactosyltransferase; C023246:ceramide glucosyltransferase; D017855:Transferases (Other Substituted Phosphate Groups); C070186:phosphatidylcholine-ceramide phosphocholine transferase