scholarly journals Sialic acid in crude myelin fractions from rat brain

1975 ◽  
Vol 148 (3) ◽  
pp. 375-380 ◽  
Author(s):  
O K Langley
Keyword(s):  
Electron Microscopy ◽  
Sialic Acid ◽  
Rat Brain ◽  
Satellite Cell ◽  
Plasma Membranes ◽  
Enzyme Assays ◽  
Marker Enzyme ◽  
Cellular Membranes ◽  
Cell Plasma ◽  
Ultrastructural Appearance

Protein- and lipid-bound sialic acid was assayed in myelin fractions isolated by four different methods from rat brain homogenates. The extent to which non-myelin cellular membranes contaminate these fractions was assessed by electron microscopy and marker-enzyme assays. Small amounts of sialic acid found in the least contaminated myelin fractions are considered to be constituents of axonal and satellite cell plasma membranes known to be present. The data are discussed with reference to the ultrastructural appearance of myelin.

scholarly journals A rapid method for the preparation of relatively pure metabolically competent synaptosomes from rat brain

1978 ◽  
Vol 176 (2) ◽  
pp. 365-370 ◽  
Author(s):  
R F G Booth ◽  
J B Clark
Keyword(s):  
Electron Microscopy ◽  
Rat Brain ◽  
Rapid Method ◽  
Sucrose Gradient ◽  
Enzyme Assays ◽  
Marker Enzyme ◽  
Flotation Technique

A rapid (less than 2h) method is described for the preparation of synaptosomes from rat brain by using a discontinuous Ficoll/sucrose gradient by a flotation technique. These synaptosomes are metabolically active and minimally (less than 5%) contaminated with ‘free’ mitochondria as judged by marker-enzyme assays and electron microscopy.

20 alpha-Hydroxysteroid dehydrogenase and 17 beta-estradiol dehydrogenase localize in cytosol of human term placenta

1982 ◽  
Vol 242 (3) ◽  
pp. E178-E183
Author(s):  
R. C. Strickler ◽  
B. Tobias
Keyword(s):  
Electron Microscopy ◽  
Dehydrogenase Activity ◽  
Hydroxysteroid Dehydrogenase ◽  
Subcellular Fractions ◽  
Enzyme Assays ◽  
Marker Enzyme ◽  
Differential Centrifugation ◽  
Experimental Conditions ◽  
Human Term Placenta ◽  
Term Placenta

The 20 alpha-hydroxysteroid dehydrogenase activity in human term placenta has been localized by different investigators to nuclear, mitochondrial, microsomal, and cytosolic subcellular fractions. Furthermore, in the cytosol, 20 alpha-hydroxysteroid dehydrogenase activity may be a second function of the enzyme that mediates 17 beta-estradiol dehydrogenase activity. To search for a unique 20 alpha-hydroxysteroid dehydrogenase, human placental villous tissue, homogenized in three different buffer systems, was fractionated by differential centrifugation, and the 17 beta- and 20 alpha-activities were measured by radioisotope conversion assay. The enrichment and purity of the subcellular fractions were shown by marker enzyme assays and electron microscopy studies. Under all experimental conditions, 20 alpha-hydroxysteroid dehydrogenase activity was identified only in the 105,000 g placental cytosol: intact, osmotically ruptured, and acetone-extracted mitochondria, nuclei, and microsomes did not convert progesterone to 20 alpha-dihydroprogesterone. Furthermore, because 17 beta-estradiol dehydrogenase activity was in large part soluble in the cytosol, these localization studies are consistent with the hypothesis that the 20 alpha- and 17 beta-oxidoreductase activities in human placenta reside on one soluble protein.

scholarly journals HELA CELL PLASMA MEMBRANES

1974 ◽  
Vol 63 (2) ◽  
pp. 357-363 ◽  
Author(s):  
Sven Johnsen ◽  
Torbjørn Stokke ◽  
Hans Prydz
Keyword(s):  
Plasma Membrane ◽  
Hela Cell ◽  
Membrane Fraction ◽  
Phase Contrast ◽  
Plasma Membranes ◽  
Specific Activity ◽  
Balance Sheet ◽  
Marker Enzyme ◽  
Plasma Membrane Fraction ◽  
Cell Plasma

A method for the preparation of HeLa cell plasma membrane ghosts is described. The purity of the plasma membrane fraction was examined by phase contrast and electron microscopy, by chemical analysis, and by assay of marker enzymes. Data on the composition of the plasma membrane fraction are given. It was observed that the distribution pattern of 5'-nucleotidase activity among the subcellular fractions differed from that of ouabain-sensitive ATPase. In addition, the specific activity of 5'-nucleotidase did not follow the distribution of the membrane ghosts. Thus, this enzyme would seem unsuitable as a plasma membrane marker. A complete balance sheet for marker enzyme activities during the fractionation is necessary for the calculation of increase in specific activity because the activities of both 5'-nucleotidase and ouabain-sensitive ATPase might change during the fractionation procedures.

scholarly journals A Ca2+-stimulated adenosine triphosphatase in Golgi-enriched membranes of lactating murine mammary tissue

1984 ◽  
Vol 224 (1) ◽  
pp. 39-45 ◽  
Author(s):  
C D Watters
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Membrane Fraction ◽  
Plasma Membranes ◽  
Mammary Tissue ◽  
Marker Enzyme ◽  
High Affinity ◽  
Cell Plasma ◽  
Lactating Mammary Gland

A membrane fraction isolated from lactating murine mammary tissue and enriched for the Golgi membrane marker enzyme galactosyltransferase exhibited Ca2+-stimulated ATPase activity (Ca-ATPase) in 20 microM-free Mg2+ and 10 microM-MgATP, with an apparent Km for Ca2+ of 0.8 microM. Exogenous calmodulin did not enhance Ca2+ stimulation, nor could Ca-ATPase activities be detected in millimolar total Mg2+ and ATP. When assayed with micromolar Mg2+ and MgATP the Ca-ATPases of skeletal-muscle sarcoplasmic reticulum and of calmodulin-enriched red blood cell plasma membranes were half-maximally activated by 0.1 microM- and 0.6 microM-Ca2+ respectively. All three Ca-ATPases were inhibited by similar micromolar concentrations of trifluoperazine, but the Golgi activity was unaffected by quercetin in concentrations which completely inhibited both the sarcoplasmic-reticulum and red-blood-cell enzymes. The results are consistent with the hypothesis that the high-affinity Ca-ATPase is responsible for the ATP-dependent Ca2+ transport exhibited by Golgi-enriched vesicles derived from lactating mammary gland [Neville, Selker, Semple & Watters (1981) J. Membr. Biol. 61, 97-105; West (1981) Biochim. Biophys. Acta 673, 374-386].

scholarly journals Location of Sialoglycoconjugates Containing the Siaα2–3Gal and Siaα2–6Gal Groups in the Rat Hippocampus and the Effect of Aging on Their Expression

2001 ◽  
Vol 49 (10) ◽  
pp. 1311-1319 ◽  
Author(s):  
Yuji Sato ◽  
Yoshihiro Akimoto ◽  
Hayato Kawakami ◽  
Hiroshi Hirano ◽  
Tamao Endo
Keyword(s):  
Electron Microscopy ◽  
Plasma Membranes ◽  
Pyramidal Cells ◽  
Staining Intensity ◽  
Rat Hippocampus ◽  
Maackia Amurensis ◽  
Ca1 Region ◽  
Old Rats ◽  
Maackia Amurensis Lectin ◽  
Stratum Lacunosum Moleculare

The histochemical distribution of sialoglycoconjugates in the CA1 region in the hippocampus formation of 9-week-old rats and 30-month-old rats was examined using electron microscopy in combination with two lectins, Maackia amurensis lectin, specific for Siaα2–3Gal, and Sambucus sieboldiana agglutinin, specific for Siaα2–6Gal. Each lectin stained the plasma membranes of pyramidal cells, indicating that the Siaα2–3Gal and Siaα2–6Gal groups were expressed on their plasma membranes. These lectins also bound to synapses in the stratum lacunosum moleculare. The staining intensity of the lectins in the synapses in these layers was downregulated in the 30-month-old rats. These results indicated that both the Siaα2–3Gal and Siaα2–6Gal groups are expressed on these synapses and that the expression of these sialyl linkages decreases in the aged brain.

Evidence of an insulin generated pyruvate dehydrogenase stimulating factor in rat brain plasma membranes

1987 ◽  
Vol 19 (10) ◽  
pp. 909-913 ◽  
Author(s):  
M.T. Rinaudo ◽  
M. Curto ◽  
R. Bruno ◽  
C. Marino ◽  
V. Rossetti ◽  
...  
Keyword(s):  
Rat Brain ◽  
Pyruvate Dehydrogenase ◽  
Plasma Membranes ◽  
Stimulating Factor

scholarly journals Insulin-induced rapid decrease of a major protein in fat cell plasma membranes.

1984 ◽  
Vol 259 (19) ◽  
pp. 12112-12116
Author(s):  
E J Schoenle ◽  
L D Adams ◽  
D W Sammons
Keyword(s):  
Plasma Membranes ◽  
Rapid Decrease ◽  
Major Protein ◽  
Fat Cell ◽  
Cell Plasma
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