Properties of Membrane-Bound Uridine Diphosphate N-Acetylglucosamine-Asparagine Sequon N-Acetylglucosaminyltransferase in Preparations of Endoplasmic Reticulum from Rabbit Liver and from Regenerating Rat Liver

1977 ◽  
Vol 5 (5) ◽  
pp. 1337-1340 ◽  
Author(s):  
ZHILA KHALKHALI ◽  
FRANCA SERAFINI-CESSI ◽  
R. DEREK MARSHALL
Keyword(s):  
Endoplasmic Reticulum ◽  
Rat Liver ◽  
Rabbit Liver ◽  
Uridine Diphosphate ◽  
Regenerating Rat Liver ◽  
Membrane Bound

scholarly journals The UDP-N-acetylglucosamine-asparagine-sequon N-acetyl-β-D-glucosaminyltransferase activity in preparations of rough endoplasmic reticulum from regenerating rat liver

1977 ◽  
Vol 164 (1) ◽  
pp. 257-261 ◽  
Author(s):  
Z Khalkhali ◽  
F Serafini-Cessi ◽  
R D Marshall
Keyword(s):  
Endoplasmic Reticulum ◽  
Partial Hepatectomy ◽  
Rat Liver ◽  
Rough Endoplasmic Reticulum ◽  
Rabbit Liver ◽  
Regenerating Rat Liver

The UDP-N-acetylglucosamine-asparagine-sequon N-acetylglucosaminyltransferase activity in preparations of rough endoplasmic reticulum from rat liver is less than 1% of that in preparations from rabbit liver. The activity of the enzyme is increased about 20-fold in preparations from regenerating rat liver within 48h after partial hepatectomy. A smaller, but still marked, increase (8-10-fold) occurs in preparations of rough endoplasmic reticulum from sham-operated rats.

Studies on the site of addition of sialic acid and glucosamine to rat α1-acid glycoprotein

1977 ◽  
Vol 55 (4) ◽  
pp. 408-414 ◽  
Author(s):  
J. C. Jamieson
Keyword(s):  
Endoplasmic Reticulum ◽  
Sialic Acid ◽  
Rat Liver ◽  
Golgi Complex ◽  
Smooth Endoplasmic Reticulum ◽  
Main Site ◽  
Acid Glycoprotein ◽  
Membrane Bound ◽  
Polypeptide Chains

Ultrasonic extracts of rough and smooth endoplasmic reticulum fractions and Golgi fractions from rat liver were examined by immunoelectrophoresis using antiserum to α1-acid glycoprotein. Rough endoplasmic reticulum fractions contained only sialic acid free α1-acid glycoprotein, whereas smooth endoplasmic reticulum and Golgi fractions also contained sialic acid containing α1-acid glycoprotein. Determination of the sialic acid contents of immune precipitates isolated from the extracts suggested that the Golgi complex was the main site of addition of sialic acid to α1-acid glycoprotein. Immunological studies on puromycin extracts of polyribosomes showed that polypeptide chains of α1-acid glycoprotein and albumin were assembled mainly on membrane-bound polyribosomes. Evidence is presented from incorporation studies with labelled leucine and glucosamine that initial glycosylation of α1-acid glycoprotein occurs mainly or entirely after release of nascent polypeptide from the ribosomal site.

Plasma membrane-bound carbonic anhydrase activity in the regenerating rat liver

1991 ◽  
Vol 1061 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Jose Juan García Marín ◽  
Arancha Tabernero Urbieta ◽  
Fernando Pérez Barriocanal ◽  
Emilio Rodríguez Barbero ◽  
Nelida Eleno
Keyword(s):  
Plasma Membrane ◽  
Carbonic Anhydrase ◽  
Rat Liver ◽  
Carbonic Anhydrase Activity ◽  
Regenerating Rat Liver ◽  
Membrane Bound

Nuclear membrane-bound UDPglucuronosyltransferase of rat liver

1982 ◽  
Vol 60 (10) ◽  
pp. 972-979 ◽  
Author(s):  
Jan Zaleski ◽  
Surendra K. Bansal ◽  
Teresa Gessner
Keyword(s):  
Endoplasmic Reticulum ◽  
High Activity ◽  
Rat Liver ◽  
Nuclear Membrane ◽  
Glucuronic Acid ◽  
Microsomal Enzyme ◽  
Subcellular Membrane ◽  
Membrane Bound ◽  
Specific Activities

Some properties of rat liver nuclear membrane-bound UDPglucuronosyltransferase were compared with those of the endoplasmic reticulum bound enzyme. The activity of nuclear membrane-bound UDPglucuronosyltransferase was stimulated only about 1.5-fold by Lubrol WX. Under the same conditions microsomal UDPglucuronosyltransferase was, as usual, highly activated (up to 10-fold), when 4-nitrophenol was the acceptor of glucuronic acid. Specific activities of the detergent-activated enzyme were similar in microsomal and nuclear membrane preparations, when the following aglycone substrates were used: 4-methylumbelliferone, 4-nitrophenol, 1-naphthol, phenolphthalein, and testosterone. Apparent Km values for UDP-glucuronic acid ranged between 0.15–0.25 mM for glucuronidation of 4-nitrophenol and 1-naphthol, by either Lubrol WX activated or non-activated, nuclear membrane-bound UDPglucuronosyltransferase. These values were comparable to those found for detergent activated microsomal enzyme. The results show a similarity in behavior of detergent-activated UDPglucuronosyltransferase regardless of subcellular membrane source and, therefore, suggest the association of the same glucuronosyltransferase with nuclear membrane and endoplasmic reticulum. A possible significance of the presence of high activity of this enzyme in nuclear membrane is discussed.

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 Role of membrane-bound and free polyribosomes in the synthesis of cytochrome c in rat liver

1974 ◽  
Vol 140 (2) ◽  
pp. 157-167 ◽  
Author(s):  
Néstor F. González-Cadavid ◽  
Carmen Sáez De Córdova
Keyword(s):  
Endoplasmic Reticulum ◽  
Cytochrome C ◽  
Rat Liver ◽  
Cell Structure ◽  
Polyacrylamide Gel Electrophoresis ◽  
Mitochondrial Protein ◽  
Sodium Dodecyl ◽  
Membrane Bound

The functional distinction of membrane-bound and free polyribosomes for the synthesis of exportable and non-exportable proteins respectively is not so strict as was initially thought, and it was therefore decided to investigate their relative contribution to the elaboration of an internal protein integrated into a cell structure. Cytochrome c was chosen as an example of a soluble mitochondrial protein, and the incorporation of [14C]leucine and δ-amino[14C]laevulinate into the molecule was studied by using different ribosomal preparations from regenerating rat liver. A new procedure was devised for the purification of cytochrome c, based on ion-exchange chromatography combined with sodium dodecyl sulphate–polyacrylamide-gel electrophoresis. In spite of cytochrome c being a non-exportable protein, the membrane-bound polyribosomes were at least as active as the free ribosomes in the synthesis in vitro of the apoprotein and the haem moiety. The detergent-treated ribosomes could also effect the synthesis of cytochrome c, although at a lower rate. Since in liver more than two-thirds of the ribosomes are bound to the endoplasmic-reticulum membranes, it is considered that in vivo they are responsible for the synthesis of most of the cytochrome c content of the cell. This suggests that in secretory tissues the endoplasmic reticulum plays a predominant role in mitochondrial biogenesis, although free ribosomes may participate in the partial turnover of some parts of the organelle. The hypothesis on the functional specialization of the different kinds of ribosomes was therefore modified to account for their parallel intervention in the synthesis of proteins associated with membranous structures.

scholarly journals Alteration of membrane barrier in stripped rough microsomes from rat liver on incubation with GTP: its relevance to the stimulation by this nucleotide of the dolichol pathway for protein glycosylation.

1983 ◽  
Vol 97 (2) ◽  
pp. 340-350 ◽  
Author(s):  
D Godelaine ◽  
H Beaufay ◽  
M Wibo ◽  
A M Ravoet
Keyword(s):  
Endoplasmic Reticulum ◽  
Rat Liver ◽  
Protein Glycosylation ◽  
Permeability Barrier ◽  
Endoplasmic Reticulum Membrane ◽  
Uridine Diphosphate ◽  
Guanosine Diphosphate ◽  
Membrane Barrier ◽  
Dolichol Pathway ◽  
Triton X

The membrane barrier of stripped rough microsomes from rat liver is markedly altered on incubation with GTP at 37 degrees C: after 30 min the structure-linked latency of mannose-6-phosphatase was considerably reduced, and esterase and nucleoside diphosphatase were partly released into the suspension medium. This phenomenon was already maximal with 30 microM GTP and was specific for this nucleotide. Similar conditions enhance the dolichol-mediated glycosylation of protein in microsomes incubated with uridine diphosphate N-acetylglucosamine and guanosine diphosphate mannose (Godelaine, D., H. Beaufay, M. Wibo, and A. Amar-Costesec, 1979, Eur. J. Biochem., 96:17-26; Godelaine, D., H. Beaufay, and M. Wibo, 1979, Eur. J. Biochem., 96:27-34). The GTP-induced permeability and glycosylation activities evolved in parallel in rough microsomes subjected to various treatments to detach the ribosomes and were maximal after removal of congruent to 60% of the RNA. In addition, GTP had no effect of this type in smooth microsome subfractions. Triton X-100, in spite of complex inhibitory effects on glycosylation reactions, mimicked the action of GTP by increasing the amount of microsomal dolichylphosphate that reacts with uridine diphosphate N-acetylglucosamine and by enhancing synthesis of dolichylpyrophosphoryl-chitobiose at concentrations greater than 2 mg/ml. Thus, GTP may activate dolichol-mediated glycosylation reactions in stripped microsomes by lowering the permeability barrier that prevents access of sugar nucleotides to the inner aspect of the membrane. The genuine role of GTP in the functioning of the endoplasmic reticulum membrane in situ remains unknown. Because GTP seems to act only on rough microsomes, we hypothesize that this role is somehow related to biosynthesis of protein by the rough endoplasmic reticulum.

scholarly journals Determination of the intracellular distribution and pool sizes of apolipoprotein B in rabbit liver

1992 ◽  
Vol 288 (2) ◽  
pp. 413-419 ◽  
Author(s):  
J Wilkinson ◽  
J A Higgins ◽  
P H E Groot ◽  
E Gherardi ◽  
D E Bowyer
Keyword(s):  
Endoplasmic Reticulum ◽  
Apolipoprotein B ◽  
Intracellular Distribution ◽  
Subcellular Fractions ◽  
Rabbit Liver ◽  
Very Low Density Lipoproteins ◽  
Apo B ◽  
Golgi Region ◽  
Membrane Bound ◽  
Vldl Assembly

We have investigated the intracellular distribution of apolipoprotein B (apo B) in rabbit liver by immunoblotting, radioimmunoassay (r.i.a.) and enzyme-linked immunoassay (e.l.i.s.a.). Apo B100 was detected in total microsomes, rough microsomes, smooth microsomes, trans-enriched Golgi and cis-enriched Golgi and membrane and cisternal-content subfractions prepared from these fractions. There was also evidence of degradation of apo B100 in the Golgi membrane fractions. The amount of apo B in the subcellular fractions detected by competitive r.i.a. or e.l.i.s.a. ranged from 1.5 micrograms/mg of protein in the rough endoplasmic reticulum to 13 micrograms/mg of protein in the trans-Golgi fraction. Using internal standards (NADPH-cytochrome c reductase for the endoplasmic reticulum and galactosyltransferase for the Golgi membranes) it was calculated that all the apo B of liver is recovered within the secretory compartment, with 63% of the total apo B in the endoplasmic reticulum and the remainder in the Golgi. When the subcellular fractions were separated into membranes and cisternal contents, 60%, 50%, 60% and 30% of the total apo B was recovered in the membrane of the rough microsomes, smooth microsomes, cis-Golgi and trans-Golgi respectively. Using competitive e.l.i.s.a. we found that the membrane-bound form of the apo B was exposed at the cytosolic surface of the intact subcellular fractions. These observations are consistent with a model for assembly of very-low-density lipoproteins (VLDL) in which newly synthesized apo B is incorporated into a membrane-bound pool and a lumenal pool. The membrane-bound pool not used for VLDL assembly may be degraded, possibly in the Golgi region.

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