Role of Rough and Smooth Microsomes in the Biosynthesis of Microsomal Membranes

Omura, Tsuneo; Kuriyama, Yoshiaki

doi:10.1093/oxfordjournals.jbchem.a129514

Cited by 56 publications

(14 citation statements)

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“…A similar phenomenon has also been demonstrated to occur after phenobarbital induction (18). The transfer of completed enzyme molecules from the rough to the smooth membranes is further supported by turnover studies of isolated NADPHcytochrome c reductase and cytochrome bb (19).…”

Section: Discussionsupporting

confidence: 54%

Biogenesis of microsomal membrane glycoproteins in rat liver. III. Release of glycoproteins from the Golgi fraction and their transfer to microsomal membranes.

Elhammer¹,

Svensson²,

Autuori³

et al. 1975

The Journal of Cell Biology

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The presence in the Golgi fraction ofglycoproteins destined to be incorporated into the microsomal membrane was investigated. When incubated in sucrose, washed Golgi vesicles released four major, weakly acidic glycoproteins, some of which could be incorporated into microsomal membranes by incubation. Double labeling with [3H]glucosamine and [l'C]leucine demonstrated the incorporation of both protein and oligosaccharide moieties, and the main peak of radioactivity was associated with the 70,000 mol wt region after SDS-gel electrophoresis. The proteins that could be incorporated into microsomes were probably associated to a large extent with the outer surface of the Golgi membrane. Centrifugation of the proteins released from the Golgi in a KBr solution (p = 1.24) resulted in a separation of glycoproteins, those in the top layer being most actively incorporated into microsomes. The lipoglycoproteins in the top layer that could be incorporated appeared in the 70,000 mol wt region after SDS-gel electrophoresis, as did the corresponding proteins isolated from the supernate. These results suggest that glycoproteins with completed oligosaccharide chains are released from the Golgi system to the cytosol and are subsequently transferred to microsomes as constitutive membrane components.

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Section: Discussionsupporting

confidence: 54%

Biogenesis of microsomal membrane glycoproteins in rat liver. III. Release of glycoproteins from the Golgi fraction and their transfer to microsomal membranes.

Elhammer¹,

Svensson²,

Autuori³

et al. 1975

The Journal of Cell Biology

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“…With respect t o the third alternative, much attention has been brought to bear on the possible significance of membrane association of ribosomes. It has been proposed that in eucaryotes, the membrane associated ribosomes are the sites of synthesis of membrane proteins (44)(45)(46)(47) and free ribosomes are the sites of synthesis of soluble proteins (48)(49)(50)(51). [For a recent treatment of the subject, see Borgese et a]., (52).]…”

Section: Studies Similar T O Ours Have Been Undertaken Bymentioning

confidence: 99%

Membrane assembly in escherichia coli V. Subcellular localization of phospholipid biosynthesis

Machtiger

Fox

1973

J Supramol Struct

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The subcellular distribution of enzymes involved in lipid biosynthesis in E. coli K 1 2 has been studied following various modes of cell disruption and fractionation of the subcellular components. Though most biosynthetic enzymes were found associated with the cytoplasmic membrane fraction regardless of the prockdures of disruption or fractionation employed, the enzymes responsible for the synthesis of the major lipid of E. coli (phosphatidylethanolamine) and of its precursor (phosphatidylserine) had no distinct localization in extracts, These findings are discussed in the context of current models for the assembly of bacterial membranes.Interest in the intracellular localization of phospholipid biosynthetic enzymes in gram negative bacteria has been stimulated by two general observations: 1. The cell envelopes of these organisms are composed of two distinct membranous layers, an inner (cytoplasmic) membrane and an outer membrane which is rich in lipopolysaccharide and localized external t o the cell wall (1 -5). 2. Interrelationships between lipid and membra'ne protein synthesis have been demonstrated for a number of membrane-associated enzyme systems (6-1 7). With respect to the first stated observation, Kennedy, Vagelos, and their associates had shown that most phospholipid biosynthetic activities co-sediment with the cell envelope (1 8-24). This raised the question as to whether the lipids in the inner and outer membranes are synthesized in one or both of these membranes. The solution t o this question became approachable only recently with the advent of techniques for separating the various fractions of the cell envelope. The second stated observation suggests a mechanism which makes newly synthesized lipids accessible t o newly synthesized proteins for their coordinated insertion into membrane. in gram negative bacteria were published during the course of our investigation. Though the three studies are in agreement on most points, the localization of phosphatidylserine synthetase was left unresolved in two of them (25,26), whereas this enzyme was reported to be localized in the ribosomal fraction in the third (27). Our data, however, did not indicate a ribosomal localization for this enzyme, nor were they in total agreement on the localization of yet another enzyme. Since different strains and/or cell disruptionThe results of three studies on the localization of phospholipid biosynthetic enzymes *The preceding paper in this series is Ref. 16. A preliminary report of this work was presented at the 72nd annual meeting of the

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“…In a limited number of cases, it has been shown that the free and membrane-bound ribosomes are indeed involved in the synthesis of different classes of proteins (3,(7)(8)(9)(10)(11), in agreement with the generalization mentioned above. There is, however, indirect evidence that in mammalian hepatocytes the bound ribosomes synthesize not only secretory proteins but also proteins of the endoplasmic reticulum membrane (12)(13)(14)(15)(16).…”

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confidence: 99%

Attachment of Chloroplast Polysomes to Thylakoid Membranes in Chlamydomonas reinhardtii

Chua

Blobel

Siekevitz

et al. 1973

Proc. Natl. Acad. Sci. U.S.A.

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Treatment of synchronous cultures of Chlamydomonas reinhardtii with chloramphenicol at 4 hr after the beginning of the light phase led to a preferential loss of 70S ribosomes from the 17,000 X gmax supernate. The "lost" 70S ribosomes were found associated with a thylakoid membrane fraction prepared from the 17,000 X gm. pellet. Electron microscopic examinations of this fraction revealed that the 70S ribosomes were bound to the unstacked regions of the thylakoid membranes as polygonal penta-and hexamers. These bound ribosomes were only released by treatment with 500 mM KCI and puromycin, suggesting that both ionic interactions and nascent peptide chains were involved in the ribosome-membrane attachment. Since growth of the thylakoid membranes occurs in the light, it is suggested that bound chloroplast ribosomes function in the synthesis of thylakoid membrane proteins.Eukaryotic ribosomes (80 S) occur in two distinct states within the cytoplasm of animal cells: they are either free or bound to the membranes of the endoplasmic reticulum (1, 2). The relative distribution of the two ribosome classes greatly depends on the cell type. Thus, cells active in the synthesis of secretory proteins contain a large proportion of bound ribosomes (3, 4), whereas cells synthesizing proteins primarily for intracellular use have most of their ribosomes in the free state (5,6). In a limited number of cases, it has been shown that the free and membrane-bound ribosomes are indeed involved in the synthesis of different classes of proteins (3,(7)(8)(9)(10)(11), in agreement with the generalization mentioned above. There is, however, indirect evidence that in mammalian hepatocytes the bound ribosomes synthesize not only secretory proteins but also proteins of the endoplasmic reticulum membrane (12-16).Since chloroplasts contain their own ribosomes (70 S), and since their is evidence that these ribosomes synthesize some of the proteins of the thylakoid membranes (17-20), the question arises as to whether these ribosomes also exist as two distinct classes within the chloroplast. In this paper, we demonstrate that in synchronous cultures of Chlamydomonas reinhardtii a detectable fraction of the chloroplast ribosome population becomes bound to the thylakoid membranes during the light phase of the cell cycle at the time when growth of the thylakoid membranes occurs. The correlation suggests that these bound ribosomes are involved in synthesis of thylakoid membrane proteins. Experiments were performed when the cultures reached a cell density of 1 to 2 X 106 cells per ml. Each culture was divided into two equal portions 4 hr after the beginning of the light phase. To one sample, chloramphenicol was added from a stock solution of 100 mg of chloramphenicol per ml of ethanol to give a final concentration of 100 yg/ml, the control sample receiving an equivalent amount of ethanol (final concentration, 0.1%). Both samples were further incubated in the light for 1 hr, which brought the cultures to the 5th hr of the light phase. At this time, t...

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Role of Rough and Smooth Microsomes in the Biosynthesis of Microsomal Membranes

Cited by 56 publications

References 0 publications

Biogenesis of microsomal membrane glycoproteins in rat liver. III. Release of glycoproteins from the Golgi fraction and their transfer to microsomal membranes.

Biogenesis of microsomal membrane glycoproteins in rat liver. III. Release of glycoproteins from the Golgi fraction and their transfer to microsomal membranes.

Membrane assembly in escherichia coli V. Subcellular localization of phospholipid biosynthesis

Attachment of Chloroplast Polysomes to Thylakoid Membranes in Chlamydomonas reinhardtii

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