Ceramide transport from endoplasmic reticulum to Golgi apparatus is not vesicle-mediated.
Ceramide (Cer) transfer from the endoplasmic reticulum (ER) to the Golgi apparatus was measured under conditions that block vesicle-mediated protein transfer. This was done either in intact cells by reducing the incubation temperature to 15 degreesC, or in streptolysin O-permeabilized cells by manipulating the intracellular environment. In both cases, Cer transfer was not inhibited, as demonstrated by the biosynthesis of ceramide monohexosides and sphingomyelin (SM) de novo from metabolically (with [14C]serine) labelled Cer. This assay is based on the knowledge that Cer is synthesized, starting from serine and palmitoyl-CoA, at the ER, whereas glycosphingolipids and SM are synthesized in the (early) Golgi apparatus. Formation of [14C]glycosphingolipids and [14C]SM was observed under conditions that block vesicle-mediated vesicular stomatitis virus glycoprotein transport. These results indicate that [14C]Cer is transferred from ER to Golgi by a non-vesicular mechanism.
University of Groningen, Department of Physiological Chemistry, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands. j.w.kok@med.rug.nl
J W
JW
Kok
T
T
Babia
K
K
Klappe
G
G
Egea
D
D
Hoekstra
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001426:Bacterial Proteins; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D002250:Carbon Radioisotopes; D002463:Cell Membrane Permeability / Q000187:drug effects; D002518:Ceramides / Q000096:biosynthesis / Q000378:metabolism* / Q000493:pharmacokinetics; D002851:Chromatography, High Pressure Liquid; D003080:Cold Temperature; D003600:Cytosol / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006028:Glycosphingolipids / Q000096:biosynthesis; D006056:Golgi Apparatus / Q000378:metabolism*; D019073:HT29 Cells / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D008562:Membrane Glycoproteins; D051381:Rats; D012694:Serine / Q000378:metabolism; D013109:Sphingomyelins / Q000096:biosynthesis; D013301:Streptolysins / Q000494:pharmacology; D014759:Viral Envelope Proteins / Q000378:metabolism
D001426:Bacterial Proteins; D002250:Carbon Radioisotopes; D002518:Ceramides; C028391:G protein, vesicular stomatitis virus; D006028:Glycosphingolipids; D008562:Membrane Glycoproteins; D013109:Sphingomyelins; D013301:Streptolysins; D014759:Viral Envelope Proteins; C025964:streptolysin O; D012694:Serine; D000255:Adenosine Triphosphate; D002118:Calcium