scholarly journals HYDROLYSIS OF CARBAMOYL PHOSPHATE IN THE ENDOPLASMIC RETICULUM AND NUCLEAR ENVELOPE OF RAT LIVER

1968 ◽  
Vol 16 (8) ◽  
pp. 546-547 ◽  
Author(s):  
AKIRA MIZUTANI ◽  
HAJIME FUJITA
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Rat Liver ◽  
Carbamoyl Phosphate ◽  
Hydrolysis Of

scholarly journals Relationship between peroxisomes and endoplasmic reticulum investigated by combined catalase and glucose-6-phosphatase cytochemistry.

1981 ◽  
Vol 29 (11) ◽  
pp. 1263-1272 ◽  
Author(s):  
H Shio ◽  
P B Lazarow
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Rat Liver ◽  
Reaction Products ◽  
Lead Phosphate ◽  
Electron Microscopic ◽  
Phosphatase Cytochemistry ◽  
Electron Microscopic Cytochemistry ◽  
Cellular Compartments

The theoretical advantages of electron microscopic cytochemistry were utilized to look for evidence of possible connections between peroxisomes and the endoplasmic reticulum in rat liver. Established cytochemical procedures for catalase (peroxisomes) and glucose-6-phosphatase (endoplasmic reticulum) were carried out, and evidence was sought of diffusion of reaction products between the organelles. No such diffusion was observed: lead phosphate was found in the endoplasmic reticulum and in the nuclear envelope but not in peroxisomes; oxidized diaminobenzidine (DAB) was seen only in peroxisomes. In addition, both types of cytochemistry were carried out on the same tissue. The two kinds of reaction product could be distinguished by virtue of their different electron opacities. No mixing of the two reaction products was observed. These results do not support the hypothesis that peroxisomes and endoplasmic reticulum may be connected; rather, they support the idea that the two organelles exist as separate cellular compartments.

scholarly journals Properties of membrane-bound bilirubin UDP-glucuronyltransferase in rough and smooth endoplasmic reticulum and in the nuclear envelope from rat liver

1989 ◽  
Vol 259 (3) ◽  
pp. 659-663 ◽  
Author(s):  
F Vanstapel ◽  
L Hammaker ◽  
K Pua ◽  
N Blanckaert
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Rat Liver ◽  
Smooth Endoplasmic Reticulum ◽  
Membrane System ◽  
Permeability Barrier ◽  
Membrane Bound ◽  
Marker Studies ◽  
High Degree ◽  
Regulatory Properties

We examined regulatory properties of bilirubin UDP-glucuronyltransferase in sealed RER (rough endoplasmic reticulum)- and SER (smooth endoplasmic reticulum)-enriched microsomes (microsomal fractions), as well as in nuclear envelope from rat liver. Purity of membrane fractions was verified by electron microscopy and marker studies. Intactness of RER and SER vesicles was ascertained by a high degree of latency of the lumenal marker mannose-6-phosphatase. No major differences in the stimulation of UDP-glucuronyltransferase by detergent or by the presumed physiological activator, UDPGlcNAc, were observed between total microsomes and RER- or SER-enriched microsomes. Isolated nuclear envelopes were present as a partially disrupted membrane system, with approx. 50% loss of mannose-6-phosphatase latency. The nuclear transferase had lost its latency to a similar extent, and the enzyme failed to respond to UDPGlcNAc. Our results underscore the necessity to include data on the integrity of the membrane permeability barrier when reporting regulatory properties of UDP-glucuronyltransferase in different membrane preparations.

scholarly journals THE USE OF THIOL-SUBSTITUTED CARBOXYLIC ACIDS AS HISTOCHEMICAL SUBSTRATES

1965 ◽  
Vol 13 (8) ◽  
pp. 611-628 ◽  
Author(s):  
MARY BELL ◽  
RUSSELL J. BARRNETT
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Lipid Metabolism ◽  
Light Microscopy ◽  
Nuclear Envelope ◽  
Carboxylic Acids ◽  
Structural Level ◽  
Low Concentrations ◽  
Hydrolysis Of ◽  
Thiolacetic Acid

Thiobutyric, thiocaproic and thiocaprylic acids were synthesized, and enzyme histochemical methods were developed using these thiol-substituted carboxylic acids, as well as thiolacetic acid, as substrates with Pb++ as the capture reagent. The localization of final product of these histochemical reactions, PbS, was studied and compared in a variety of tissues with light microscopy. The enzymatic activities demonstrated were sensitive to low concentrations of E600. The localization of these reactions in several intensely reactive tissues, liver, testis and intestine, were also studied with electron microscopy. At a fine structural level, the final product was deposited primarily in relation to the membranous elements of the smooth and rough varieties of the endoplasmic reticulum, including the nuclear envelope, and of mitochondria. The results of these experiments are discussed, including the possible identity of the enzymes concerned with the hydrolysis of the thiol-substituted substrates. It was suggested that at least three activities were demonstrated in these experiments, one of which was the B type esterase of microsomes, and all of which functioned in lipid metabolism.

The Role of Membrane Proteins and Phospholipids in the Interaction of Ribosomes with Endoplasmic Reticulum Membranes

1975 ◽  
Vol 53 (9) ◽  
pp. 1039-1045 ◽  
Author(s):  
Serge Jothy ◽  
Jean-Louis Bilodeau ◽  
Henry Simpkins
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Rat Liver ◽  
Rough Endoplasmic Reticulum ◽  
Binding Sites ◽  
Molecular Weights ◽  
Low Concentrations ◽  
Phospholipid Headgroups ◽  
Hydrolysis Of

Hydrolysis of the membrane proteins and phospholipid headgroups of rat liver rough endoplasmic reticulum membranes showed that the ribosomal binding sites involve membrane proteins susceptible to low concentrations of trypsin, chymotrypsin, and papain. Three membrane proteins having molecular weights of 120 000, 93 000 and 36 000 are found to be altered by trypsin and chymotrypsin treatment. Also the polar headgroup of phosphatidylinositol appears to play a role in the binding process.

scholarly journals Rat liver nuclear skeleton and small molecular weight RNA species.

1978 ◽  
Vol 76 (3) ◽  
pp. 692-704 ◽  
Author(s):  
T E Miller ◽  
C Y Huang ◽  
A O Pogo
Keyword(s):  
Molecular Weight ◽  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Rat Liver ◽  
Protein Matrix ◽  
Small Molecular Weight ◽  
Rat Liver Nuclei ◽  
Nuclear Rna ◽  
Liver Nuclei ◽  
Preceding Communication

Small molecular weight RNA species (smwRNAs) were studied in rat liver nuclei with and without chromatin as well as with and without nuclear envelope and nucleoplasm. From all the species identified, only two, N5 and 5Sb, were related to ribosomes. The others were localized exclusively in the nuclear skeleton or the spongelike network that was described in the preceding communication. This network or protein matrix contains a less abundant but exclusive set of molecules designated 5Sa, N1, and 4.5S, as well as other more abundant molecules which also exist in rat liver endoplasmic reticulum but not in polysomes or postribosomal RNP complexes. The smwRNAs behave like HnRNA; they remain located in the nuclear skeleton when nuclei are deprived of nucleoplasm and chromatin. With the information presently available, it is not possible to know whetherer both species are in the same or different RNP complexes and whether some of the smwRNAs contribute to the architecture of the nuclear skeleton. Distinct from any other nuclear RNA species, smwRNAs have two unique properties: facility of extraction, and resistance to nuclear ribonuclease digestion.

scholarly journals CYTOCHEMICAL STUDIES ON HYDROLYSIS OF CARBAMOYL PHOSPHATE IN RAT LIVER

1968 ◽  
Vol 1 (2) ◽  
pp. 79-94 ◽  
Author(s):  
AKIRA MIZUTANI ◽  
HAJIME FUJITA
Keyword(s):  
Rat Liver ◽  
Carbamoyl Phosphate ◽  
Hydrolysis Of

scholarly journals THE FINE STRUCTURAL LOCALIZATION OF GLUCOSE-6-PHOSPHATASE IN RAT LIVER

1962 ◽  
Vol 10 (6) ◽  
pp. 754-762 ◽  
Author(s):  
LOIS W. TICE ◽  
RUSSELL J. BARRNETT
Keyword(s):  
Endoplasmic Reticulum ◽  
Enzyme Activity ◽  
Plasma Membrane ◽  
Electron Microscope ◽  
Nuclear Envelope ◽  
Phosphatase Activity ◽  
Rat Liver ◽  
Structural Localization ◽  
Hepatic Cells ◽  
Fixed Material

Glucose-6-phosphatase activity was demonstrated histochemically in rat liver using either the Wachstein-Meisel medium or a modified Chiquoine medium, and the characteristic properties of the enzyme activity were confirmed. The distribution of activity in both unfixed and hydroxyadipaldehyde-fixed material was demonstrated with the electron microscope. Activity was found in both smooth- and rough-surfaced elements of the endoplasmic reticulum of hepatic cells, including the nuclear envelope, but was absent from the plasma membrane. These findings further implicate the endoplasmic reticulum as an organelle of transport, and in addition suggest that the nuclear envelope has functional as well as morphological continuity with the endoplasmic reticulum.

Biosynthesis of Mitochondrial Phospholipids Using Endogenously Generated Diglycerides

1975 ◽  
Vol 53 (7) ◽  
pp. 784-795 ◽  
Author(s):  
W. C. McMurray
Keyword(s):  
Endoplasmic Reticulum ◽  
Phosphatidic Acid ◽  
Phospholipase C ◽  
Rat Liver ◽  
De Novo ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Isolated Mitochondria ◽  
Hydrolysis Of ◽  
Stimulation Of

When isolated mitochondria or microsomes from rat liver were treated with phospholipase C, the incorporation of radioactive phospholipid precursors was markedly enhanced, presumably as a result of production of diglycerides by hydrolysis of endogenous phospholipids. Incorporation of CDP[14C]choline into lecithin in rat liver or BHK-21 mitochondria could be attributed to residual contamination from elements of the endoplasmic reticulum, with added diglycerides or with endogenous diglycerides produced by the phospholipase C treatment. A similar stimulation of [γ32P]ATP incorporation into phospholipids was observed with exogenous or endogenous diglycerides, but the mitochondrial diglyceride kinase in either case was also related to the degree of microsomal contaminants. It was concluded that previous studies showing negligible capacity of mitochondria for lecithin biosynthesis de novo were not explainable on the basis of limited accessibility of added diglycerides, and that formation of phosphatidic acid by diglyceride kinase was not of significance in rat liver mitochondria.

scholarly journals Carrier-mediated transport of intact UDP-glucuronic acid into the lumen of endoplasmic-reticulum-derived vesicles from rat liver

1994 ◽  
Vol 302 (1) ◽  
pp. 261-269 ◽  
Author(s):  
X Bossuyt ◽  
N Blanckaert
Keyword(s):  
Endoplasmic Reticulum ◽  
Rat Liver ◽  
Glucuronic Acid ◽  
Double Labelling ◽  
Carrier Mediated Transport ◽  
Cytosolic Side ◽  
Stimulation Experiments ◽  
Uptake Studies ◽  
Rapid Hydrolysis ◽  
Hydrolysis Of

Uptake and metabolism of UDP-glucuronic acid (UDPGlcA) by rough-endoplasmic-reticulum (RER)-derived vesicles was studied. Analysis of the molecular species, double-labelling experiments and trans-stimulation experiments revealed that initial uptake represented entry into microsomes of predominantly intact UDPGlcA, concomitant with rapid hydrolysis of the internalized nucleotide sugar. The uptake constituted effective translocation from the medium into the lumen of the vesicles. Thus the amount of vesicle-associated label at equilibrium uptake was directly proportional to the volume of the intravesicular space. Permeabilized microsomes were unable to retain UDPGlcA. The microsomal uptake of UDPGlcA met the criteria of bidirectional carrier-mediated translocation. Transport was time- and temperature-dependent, saturable, selective, capable of trans-stimulation, and operational against a concentration gradient. Microsomal uptake was inhibited by N-ethylmaleimide that was presented at the cytosolic side of the endoplasmic-reticulum (ER) membrane. Uptake studies performed in membrane preparations that were highly enriched in RER, smooth ER or Golgi revealed that UDPGlcA was taken up by the ER as well as by the Golgi apparatus. Our findings demonstrate the existence in rat liver ER of a carrier system mediating proper translocation of intact UDPGlcA across the membrane.

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