scholarly journals The subcellular distribution of rat liver serine-pyruvate aminotransferase

1982 ◽  
Vol 202 (2) ◽  
pp. 483-490 ◽  
Author(s):  
K V Rowsell ◽  
L M R Al-Naama ◽  
P Benett
Keyword(s):  
Rat Liver ◽  
Subcellular Distribution ◽  
Subcellular Location ◽  
Mitochondrial Activity ◽  
Transferase Activity ◽  
Mitochondrial Enzymes ◽  
Marker Enzymes ◽  
Aminotransferase Activity ◽  
Mitochondrial Marker ◽  
Differential Sedimentation

1. The subcellular distribution of L-serine-pyruvate aminotransferase activity in rat liver was investigated. About 80% was recovered from cell-free homogenates in a ‘total-particles’ fraction and the remainder in the cytosol. 2. Subfractionation of the particles by differential sedimentation and on sucrose density gradients showed a distribution for serine-pyruvate aminotransferase activity closely matching that observed for mitochondrial marker enzymes. 3. A study of the solubilization of enzymes from combined subcellular particles by digitonin at various concentrations also indicated a common subcellular location for serine-pyruvate aminotransferase and established mitochondrial enzymes. 4. The increase in liver serine-pyruvate amino-transferase activity induced by glucagon injection was accounted for as an increased mitochondrial activity.

scholarly journals Studies on the glutathione S-transferase activity associated with rat liver mitochondria

1984 ◽  
Vol 222 (2) ◽  
pp. 553-556 ◽  
Author(s):  
C M Ryle ◽  
T J Mantle
Keyword(s):  
Lactate Dehydrogenase ◽  
Rat Liver ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Transferase Activity ◽  
Marker Enzymes ◽  
Glutathione S Transferase ◽  
Mitochondrial Marker ◽  
Liver Glutathione

The major proportion of rat liver glutathione S-transferase is cytosolic. Carefully washed mitochondria contain 0.25-0.47% of the cytosolic activity. Subfractionation of washed mitochondria using digitonin treatment revealed that glutathione S-transferase release did not parallel that of any of the mitochondrial marker enzymes. Glutathione S-transferase release paralleled that of lactate dehydrogenase, suggesting that these ‘mitochondrial’ activities are due to loosely bound cytoplasmic forms.

scholarly journals The subcellular distribution of rat liver l-alanine–glyoxylate aminotransferase in relation to a pathway for glucose formation involving glyoxylate

1972 ◽  
Vol 127 (1) ◽  
pp. 155-165 ◽  
Author(s):  
E. V. Rowsell ◽  
K. Snell ◽  
J. A. Carnie ◽  
Kathleen V. Rowsell
Keyword(s):  
Rat Liver ◽  
High Speed ◽  
Mitochondrial Enzymes ◽  
Aminotransferase Activity ◽  
Ph Optimum ◽  
Cytosol Fraction ◽  
Specific Association ◽  
Differential Sedimentation ◽  
Glyoxylate Aminotransferase ◽  
Glucose Formation

1. The distribution of l-alanine–glyoxylate aminotransferase activity between subcellular fractions prepared from rat liver homogenates was investigated. The greater part of the homogenate activity (about 80%) was recovered in the `total-particles' fraction sedimented by high-speed centrifugation and the remainder in the cytosol fraction. 2. Subfractionation of the particles by differential sedimentation and on sucrose density gradients revealed a specific association between the aminotransferase and the mitochondrial enzymes glutamate dehydrogenase and rhodanese. 3. The aminotransferase activities in the cytosol and the mitochondria are due to isoenzymes. The solubilized mitochondrial enzyme has a pH optimum of 8.6, an apparent Km of 0.24mm with respect to glyoxylate and is inhibited by glyoxylate at concentrations above 5mm. The cytosol aminotransferase shows no distinct pH optimum (over the range 7.0–9.0) and has an apparent Km of 1.11mm with respect to glyoxylate; there is no evidence of inhibition by glyoxylate. 4. The mitochondrial location of the bulk of the rat liver l-alanine–glyoxylate aminotransferase activity is discussed in relation to a pathway for gluconeogenesis involving glyoxylate.

scholarly journals Subcellular localization of ornithine decarboxylase in liver of control and growth-hormone-treated rats

1976 ◽  
Vol 157 (1) ◽  
pp. 33-39 ◽  
Author(s):  
B J Murphy ◽  
M E Brosnan
Keyword(s):  
Growth Hormone ◽  
Ornithine Decarboxylase ◽  
Rat Liver ◽  
Subcellular Fractionation ◽  
Decarboxylase Activity ◽  
Differential Centrifugation ◽  
Marker Enzymes ◽  
Aminotransferase Activity ◽  
Apparent Affinity ◽  
Hormone Administration

1. Ornithine-2-oxo acid aminotransferase activity was inhibited by amino-oxyacetate (10(-5) M). This permitted the measurement of ornithine decarboxylase in the presence of mitochondria by using the 14CO2-trapping technique. 2. Subcellular fractionation of rat liver by differential centrifugation, followed by the assay of ornithine decarboxylase in the presence of amino oxyacetate and of marker enzymes for each fraction, demonstrated that ornithine decarboxylase was located in the cytosol. 3. The greatly increased ornithine decarboxylase activity observed after growth-hormone administration was also found to be localized in the cytosol. 4. The Km of ornithine decarboxylase from rat liver for ornithine was 28 muM. Administration of growth hormone 4 h before death did not affect the apparent affinity of ornithine decarboxylase for ornithine.

scholarly journals Subcellular distribution and some properties of N-ethylmaleimide-sensitive and-insensitive forms of glycerol phosphate acyltransferase in rat adipocytes

1980 ◽  
Vol 190 (1) ◽  
pp. 183-189 ◽  
Author(s):  
E D Saggerson ◽  
C A Carpenter ◽  
C H Cheng ◽  
S R Sooranna
Keyword(s):  
Subcellular Distribution ◽  
Subcellular Fractions ◽  
Mitochondrial Activity ◽  
Dihydroxyacetone Phosphate ◽  
Marker Enzymes ◽  
Microsomal Enzyme ◽  
Glycerol Phosphate ◽  
Rat Adipocytes ◽  
Phosphatidate Phosphohydrolase ◽  
Parallel Measurements

1. Glycerol phosphate acyltransferase (GPAT) activities were measured in subcellular fractions obtained from rat epididymal adipocytes. These contained both N-ethylmaleimide-sensitive and N-ethylmaleimide-insensitive forms of the enzyme. 2. As shown by parallel measurements of marker enzymes, N-ethylmaleimide-insensitive GPAT is most probably a mitochondrial activity, whereas N-ethylmaleimide-sensitive GPAT is the microsomal enzyme. 3. Subcellular distributions are also reported for dihydroxyacetone phosphate acyltransferase (DHAPAT) (assayed with and without N-ethylmaleimide), monoacylglycerol phosphate acyltransferase (MGPAT) and Mg2+-dependent and Mg2+-independent forms of phosphatidate phosphohydrolase (PPH).

scholarly journals Subcellular localization of the enzyme that forms mannosyl retinyl phosphate from guanosine diphosphate [14C]mannose and retinyl phosphate

1979 ◽  
Vol 180 (3) ◽  
pp. 449-453 ◽  
Author(s):  
M J Smith ◽  
J B Schreiber ◽  
G Wolf
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Golgi Apparatus ◽  
Subcellular Localization ◽  
Rat Liver ◽  
Rough Endoplasmic Reticulum ◽  
Subcellular Distribution ◽  
Smooth Endoplasmic Reticulum ◽  
Marker Enzymes ◽  
Guanosine Diphosphate

The subcellular distribution of the enzyme catalysing the conversion of retinyl phosphate and GDP-[14C]mannose into [14C]mannosyl retinyl phosphate was determined by using subcellular fractions of rat liver. Purity of fractions, as determined by marker enzymes, was 80% or better. The amount of mannosyl retinyl phosphate formed (pmol/min per mg of protein) for each fraction was: rough endoplasmic reticulum 0.48 +/- 0.09 (mean +/- S.D.); smooth membranes (consisting of 60% smooth endoplasmic reticulum and 40% Golgi apparatus), 0.18 +/- 0.03; Golgi apparatus, 0.13 +/- 0.03; and plasma membrane 0.02.

Acetylcholinesterase and nonspecific cholinesterase activities in rat liver: subcellular localization, molecular forms, and some extraction properties

1989 ◽  
Vol 67 (11-12) ◽  
pp. 817-822 ◽  
Author(s):  
Patricia Berninsone ◽  
Eleonora Katz ◽  
Monica Napp ◽  
Julio Azcurra
Keyword(s):  
Rat Liver ◽  
Subcellular Distribution ◽  
Ache Activity ◽  
Smooth Endoplasmic Reticulum ◽  
Subcellular Location ◽  
High Salt ◽  
Subcellular Fractions ◽  
Velocity Sedimentation ◽  
Molecular Forms ◽  
Extraction Properties

Subcellular distribution and some extraction properties of acetylcholinesterase (AchE) (EC 3.1.1.7) and nonspecific cholinesterase (ChE) (EC 3.1.1.8) were studied in rat liver employing subcellular fractionation techniques. All purified subcellular fractions were enriched in total cholinesterase activity over the homogenate. Plasma membrane and Golgi fractions showed a significant enrichment in AchE activity, while ChE activity was enriched in both rough and smooth endoplasmic reticulum. Subcellular fractions were subjected to conditions that selectively release proteins having varying degrees of association to membranes. High-pH treatment (known to release peripheral and soluble proteins) extracted ChE activity, but more than 90% of AchE activity remained associated to the pellet. Solubility properties and molecular forms of AchE and ChE in this tissue were studied by extraction in high-salt medium with and without Triton X-100, followed by velocity sedimentation centrifugation. Most of AchE activity (88%) (41% G4 and 59% G2 + G1) was detergent soluble; 42% of ChE activity (detected only as G2 + G1) was high-salt soluble, whereas remaining ChE activity was detergent soluble. These results indicate not only a different subcellular location for both enzymes, but also point to a differential association to membranes. AchE behaves as an integral membrane protein and ChE behaves as a peripheral or a luminal soluble protein.Key words: acetylcholinesterase, membrane association, molecular forms, nonspecific cholinesterase, rat liver, subcellular distribution.

scholarly journals Digitonin perfusion of rat liver. A new approach in the study of intra-acinar and intracellular compartmentation in the liver

1985 ◽  
Vol 226 (1) ◽  
pp. 289-297 ◽  
Author(s):  
B Quistorff ◽  
N Grunnet ◽  
N W Cornell
Keyword(s):  
Rat Liver ◽  
The Other ◽  
Marker Enzymes ◽  
Mitochondrial Marker ◽  
New Approach ◽  
Cytoplasmic Material ◽  
Intracellular Compartmentation ◽  
Intracellular Compartments

Perfusing a rat liver with digitonin in the concentration range 2-20 mg/ml results in complete decolorization of the organ within 45-250 s. Decolorization progresses with time in the direction of flow, and it is therefore possible, by collecting the eluate, to obtain material from specific intracellular compartments of hepatocytes in different zones in the microcirculatory unit of the liver. The results demonstrate that cytoplasmic marker enzymes from periportal or perivenous hepatocytes can be collected with as little contamination from the other compartment as is obtained in micro-dissection studies. Furthermore, a fraction enriched in mitochondrial marker enzymes can be achieved with only 10-20% contamination by cytoplasmic material.

scholarly journals Subcellular distribution of pyruvate (glyoxylate) aminotransferases in rat liver

1978 ◽  
Vol 170 (1) ◽  
pp. 173-175 ◽  
Author(s):  
T Noguchi ◽  
Y Minatogawa ◽  
Y Takada ◽  
E Okuno ◽  
R Kido
Keyword(s):  
Rat Liver ◽  
Subcellular Distribution ◽  
Enzyme Activities ◽  
Particulate Fraction ◽  
Aminotransferase Activity ◽  
Liver Homogenates ◽  
Glucagon Injection ◽  
Glyoxylate Aminotransferase

The distribution of pyruvate (glyoxylate) aminotransferases in the particulate fraction of rat liver homogenates was examined by centrifugation in a sucrose density graident. Aminotransferase activities towards serine, phenylalanine and histidine with pyruvate and those towards phenylalanine and histidine with glyoxylate were nearly identically distributed. Some 50-55% of the particulate activity was localized in the peroxisomes and the remainder in the mitochondria. Most of alanine-glyoxylate aminotransferase activity was localized in the mitochondria, with some activity in the peroxisomes. Glucagon injection resulted in increases of these enzyme activities in the mitochondria, but not in the peroxisomes.

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