Enzyme distributions in subcellular fractions of BHK cells infected with Semliki Forest virus: evidence for a major fraction of sphingomyelin synthase in the trans-Golgi network

Citation
D. Allan et Mjm. Obradors, Enzyme distributions in subcellular fractions of BHK cells infected with Semliki Forest virus: evidence for a major fraction of sphingomyelin synthase in the trans-Golgi network, BBA-MOL CEL, 1450(3), 1999, pp. 277-287
Citations number
31
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Cell & Developmental Biology
Journal title
BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH
ISSN journal
0167-4889 → ACNP
Volume
1450
Issue
3
Year of publication
1999
Pages
277 - 287
Database
ISI
SICI code
0167-4889(19990708)1450:3<277:EDISFO>2.0.ZU;2-K
Abstract
BHK cells either untreated or infected with Semliki Forest virus have been fractionated on sucrose density gradients. Virus infection caused an increa se in density of a membrane fraction enriched in sphingomyelin (SM), choles terol, SM synthase and sialyltransferase activity. This increase in density was related to incorporation of viral proteins into this fraction, which i s likely to contain trans-Golgi network (TGN) membranes. In contrast, gluco sylceramide synthase and galactosyltransferase activities (markers for cis/ medial and trans-Golgi respectively) underwent no density shift and alkalin e phosphodiesterase, a plasma membrane marker, was only slightly density-sh ifted in infected cells. When cells were incubated with NBD-ceramide to ena ble them to synthesise NBD-SM and then washed with albumin to remove surfac e label, fluorescence in untreated cells was concentrated in a single juxta nuclear spot but in infected cells this region of bright fluorescence was l arger and extended around the nucleus. After fractionation of these cells, NBD-SM (but only a small proportion of the NBD-ceramide) was found to be sh ifted into the higher density fraction in infected cells. This work provide s further evidence that SM synthase is not mainly localised in the early Go lgi cisternae as previously thought, but is associated more with a choleste rol-rich compartment which could be the TGN. (C) 1999 Elsevier Science B.V. All rights reserved.