scholarly journals Localization of β-glucan synthases on the membranes of cultured Lolium multiflorum (ryegrass) endosperm cells

1983 ◽  
Vol 209 (3) ◽  
pp. 627-633 ◽  
Author(s):  
R J Henry ◽  
A Schibeci ◽  
B A Stone
Keyword(s):  
Density Gradient ◽  
Plasma Membranes ◽  
Lolium Multiflorum ◽  
Sucrose Density Gradient ◽  
Italian Ryegrass ◽  
Beta Glucan ◽  
Glucan Synthase ◽  
Intracellular Membranes

The distribution of beta-glucan synthases between plasma membranes and intracellular membranes of suspension-cultured Italian-ryegrass (Lolium multiflorum Lam.) endosperm cells was examined. Highly purified plasma membranes prepared from protoplasts were only slightly enriched in beta-glucan synthases assayed at 10 microM- and 1 mM-UDP-glucose. Most beta-glucan synthase was associated with intracellular membranes. These membranes were fractionated on a linear sucrose density gradient and were resolved into different membrane fractions containing beta-glucan synthases. Beta-Glucan synthases assayed at 10 microM-UDP-glucose were found in a fraction banding at a density of 1.11 g . cm-3, but most of the beta-glucan synthase assayed at 1 mM-DDP-glucose was at a density of 1.04 g . cm-3.

scholarly journals Solubilization of β-glucan synthases from the membranes of cultured ryegrass endosperm cells

1982 ◽  
Vol 203 (3) ◽  
pp. 629-636 ◽  
Author(s):  
R J Henry ◽  
B A Stone
Keyword(s):  
Lolium Multiflorum ◽  
Partial Purification ◽  
Beta Glucan ◽  
Glucan Synthase ◽  
Steryl Glucosides ◽  
Octyl Glucoside ◽  
Beta Glucans ◽  
Membrane Bound ◽  
Glucan Synthesis

beta-Glucan synthases were solubilized by treating membrane preparations from suspension-cultured ryegrass (lolium multiflorum) endosperm cells with detergents. Of the seven detergents tested only digitonin and octyl glucoside dissociated active synthases from the membranes. The digitonin-solubilized enzymes produced 1,4-beta-glucans and 1,3:1,4-beta-glucans, whereas the digitonin-insoluble enzymes produced, in addition, 1,3-beta-glucans. Chromatography of the digitonin-solubilized beta-glucan synthases on DEAE-Sepharose resulted in their partial purification. The octyl glucoside-solubilized enzymes produced more 1,3-beta-glucans than did the membrane-bound preparations. These results suggest that the 1,3-beta-glucan synthase is a separate enzyme and is not involved in 1,3:1,4-beta-glucan synthesis. Digitonin not only dissociated synthases from the membranes, but also stimulated synthase activity. This effect may be related to the inhibition by digitonin of glucosyl transfer from UDP-glucose to form steryl glucosides.

scholarly journals Organization of the phosphoinositide cycle. Assessment of inositol transferase activity in purified plasma membranes

1993 ◽  
Vol 290 (1) ◽  
pp. 179-183 ◽  
Author(s):  
O M Santiago ◽  
L I Rosenberg ◽  
M E Monaco
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Density Gradient ◽  
Plasma Membranes ◽  
Sucrose Density Gradient ◽  
Tumour Cells ◽  
Assay System ◽  
Mammary Tumour ◽  
Transferase Activity ◽  
Phosphoinositide Cycle

Experiments were carried out to determine whether or not CDP-diacylglycerol:myo-inositol 3-phosphatidyltransferase (IT) activity (EC 2.7.8.11) could be detected in purified plasma-membrane fractions from WRK-1 rat mammary tumour cells. These cells have previously been shown to have a very active phosphoinositide cycle. Sucrose-density-gradient-purified plasma membranes contained no IT activity that could not be accounted for by endoplasmic-reticulum contamination. However, we also determined that the relative amount of IT activity in endoplasmic reticulum and plasma-membrane fractions could be altered by changing the concentration of detergent in the assay system.

Evidence for copurification of micronuclei in sucrose density gradient-enriched plasma membranes from cell lines

2010 ◽  
Vol 396 (1) ◽  
pp. 69-75 ◽  
Author(s):  
Sambasivarao Damaraju ◽  
Nancy Zhang ◽  
Nan Li ◽  
Lidan Tao ◽  
Vijaya L. Damaraju ◽  
...  
Keyword(s):  
Density Gradient ◽  
Cell Lines ◽  
Plasma Membranes ◽  
Sucrose Density Gradient

Proton Motive Potential Difference Across the Plasma Membrane of Plant Cells: a Comparison of Cultured Cells and Protoplasts From Italian Ryegrass (Lolium multiflorum Lam.) Endosperm

1984 ◽  
Vol 11 (3) ◽  
pp. 119 ◽  
Author(s):  
RJ Henry ◽  
A Schibeci ◽  
BA Stone
Keyword(s):  
Plasma Membranes ◽  
Cultured Cells ◽  
Lolium Multiflorum ◽  
Electrical Potential ◽  
Italian Ryegrass ◽  
Ph Gradient ◽  
Cytoplasmic Ph ◽  
Transmembrane Electrical Potential ◽  
Main Component ◽  
External Ph

The electrochemical proton gradient (ΔμH+) was measured across the plasma membranes of ryegrass (Lolium multiflorum Lam.) endosperm cells grown in suspension culture. The pH gradient (ΔpH) and the transmembrane electrical potential (ΔΨ) of cells and protoplasts were compared. The pH gradient (ΔpH) was measured from the distribution of acetylsalicylic acid and 5,5-dimethyloxazolidine and the membrane potential (ΔΨ) was calculated from the distribution of the lipophilic tetraphenylphosphonium cation (TPP+) between the cells and medium. The protoplasts and cells maintained a similar ΔpH. At the external pH of the growth medium (pH 5.5), the cytoplasmic pH was about 7. Under these conditions the ΔΨ was -60 mV (negative inside) for cells and -46 mV for protoplasts. ΔpH and ΔΨ have values which vary reciprocally depending on the external pH. The main contributor to ΔμH+ at pH 4.0 is ΔpH whereas, at pH 7.0, ΔΨ is the main component. The external K+ concentration influences the cytoplasmic pH significantly only at the higher external pH values.

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