Lipid composition and turnover of rough and smooth microsomal membranes in rat liver
Subfractions of rat liver microsomes (rough, smooth I, and smooth II), isolated in a cation-containing sucrose gradient system, were analyzed. After removal of adsorbed and luminal protein, these subfractions had the same phospholipid/protein ratio, about 0.40. Both the classes and the relative amou...
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doaj-1aa8fa51f47149fa82ef4e4d864479642021-04-24T05:54:30ZengElsevierJournal of Lipid Research0022-22751968-11-0196720729Lipid composition and turnover of rough and smooth microsomal membranes in rat liverHans Glaumann0Gustav Dallner1Department of Pathology, Sabbatsberg Hospital, Karolinska Institute, and the Institute of Biochemistry, University of Stockholm, Stockholm, SwedenDepartment of Pathology, Sabbatsberg Hospital, Karolinska Institute, and the Institute of Biochemistry, University of Stockholm, Stockholm, SwedenSubfractions of rat liver microsomes (rough, smooth I, and smooth II), isolated in a cation-containing sucrose gradient system, were analyzed. After removal of adsorbed and luminal protein, these subfractions had the same phospholipid/protein ratio, about 0.40. Both the classes and the relative amounts of phospholipids were similar in the three subfractions, but the relative amounts of neutral lipids (predominantly free cholesterol and triglycerides) were higher in smooth I and especially in smooth II than in rough microsomes. Various pieces of evidence indicate that the neutral lipids are tightly bound to the membranes.Glycerol-3H was incorporated into the phospholipids of the rough and smooth I microsomes significantly faster than into those of the smooth II membranes; 32P incorporation followed a similar but less pronounced pattern. Acetate-3H was incorporated into the free cholesterol of smooth I microsomes only half as fast as into the other two subfractions. Injection of phenobarbital increased the cellular phospholipid and neutral lipid content in the rough and smooth I, but not in the smooth II microsomes. Consequently, the neutral lipid/phospholipid ratio of all three subfractions remained unchanged after phenobarbital treatment.It is concluded that the membranes of the rough and the two smooth microsomal subfractions from rat liver have a similar phospholipid composition, but are dissimilar in their neutral lipid content and in the incorporation rate of precursors into membrane lipids.http://www.sciencedirect.com/science/article/pii/S0022227520426847neutral lipidmembrane componentssmooth I and IIphenobarbital |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Hans Glaumann Gustav Dallner |
spellingShingle |
Hans Glaumann Gustav Dallner Lipid composition and turnover of rough and smooth microsomal membranes in rat liver Journal of Lipid Research neutral lipid membrane components smooth I and II phenobarbital |
author_facet |
Hans Glaumann Gustav Dallner |
author_sort |
Hans Glaumann |
title |
Lipid composition and turnover of rough and smooth microsomal membranes in rat liver |
title_short |
Lipid composition and turnover of rough and smooth microsomal membranes in rat liver |
title_full |
Lipid composition and turnover of rough and smooth microsomal membranes in rat liver |
title_fullStr |
Lipid composition and turnover of rough and smooth microsomal membranes in rat liver |
title_full_unstemmed |
Lipid composition and turnover of rough and smooth microsomal membranes in rat liver |
title_sort |
lipid composition and turnover of rough and smooth microsomal membranes in rat liver |
publisher |
Elsevier |
series |
Journal of Lipid Research |
issn |
0022-2275 |
publishDate |
1968-11-01 |
description |
Subfractions of rat liver microsomes (rough, smooth I, and smooth II), isolated in a cation-containing sucrose gradient system, were analyzed. After removal of adsorbed and luminal protein, these subfractions had the same phospholipid/protein ratio, about 0.40. Both the classes and the relative amounts of phospholipids were similar in the three subfractions, but the relative amounts of neutral lipids (predominantly free cholesterol and triglycerides) were higher in smooth I and especially in smooth II than in rough microsomes. Various pieces of evidence indicate that the neutral lipids are tightly bound to the membranes.Glycerol-3H was incorporated into the phospholipids of the rough and smooth I microsomes significantly faster than into those of the smooth II membranes; 32P incorporation followed a similar but less pronounced pattern. Acetate-3H was incorporated into the free cholesterol of smooth I microsomes only half as fast as into the other two subfractions. Injection of phenobarbital increased the cellular phospholipid and neutral lipid content in the rough and smooth I, but not in the smooth II microsomes. Consequently, the neutral lipid/phospholipid ratio of all three subfractions remained unchanged after phenobarbital treatment.It is concluded that the membranes of the rough and the two smooth microsomal subfractions from rat liver have a similar phospholipid composition, but are dissimilar in their neutral lipid content and in the incorporation rate of precursors into membrane lipids. |
topic |
neutral lipid membrane components smooth I and II phenobarbital |
url |
http://www.sciencedirect.com/science/article/pii/S0022227520426847 |
work_keys_str_mv |
AT hansglaumann lipidcompositionandturnoverofroughandsmoothmicrosomalmembranesinratliver AT gustavdallner lipidcompositionandturnoverofroughandsmoothmicrosomalmembranesinratliver |
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1721511380759085056 |