scholarly journals IMMUNOGLOBULIN SYNTHESIS AND SECRETION

1970 ◽  
Vol 46 (1) ◽  
pp. 52-63 ◽  
Author(s):  
Daniel Zagury ◽  
Jonathan W. Uhr ◽  
James D. Jamieson ◽  
George E. Palade
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Electron Microscope ◽  
Rough Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Immunoglobulin G ◽  
Plasma Cells ◽  
Polypeptide Chain ◽  
Polypeptide Backbone ◽  
Mouse Myeloma

The subcellular sites of synthesis and route of intracellular transfer of immunoglobulin G (IgG) have been investigated by electron microscope radioautography with precursors used for the polypeptide chain (leucine-3H) and for the carbohydrate moieties (galactose-3H and glucosamine-3H). For this purpose, plasma cells from a mouse myeloma tumor were labeled with appropriate precursors and the distribution of radioautographic grains was determined at the end of the labeling period and after varying times of incubation in unlabeled medium. The results indicated that the polypeptide backbone is synthesized in a region of the cell occupied by the rough endoplasmic reticulum (RER) and is transported from there to the region of the Golgi complex. Galactose is incorporated in IgG primarily at the level of the Golgi complex, whereas the incorporation of glucosamine appears to take place both in the RER and in the Golgi complex. From the Golgi complex, the completed IgG molecules reach the plasma membrane and are discharged extracellularly. The latter route of transport and the mechanism of discharge are not understood but may be mediated via smooth-surfaced vesicles.

scholarly journals Immunoelectron microscopic studies of the intracellular transport of the membrane glycoprotein (G) of vesicular stomatitis virus in infected Chinese hamster ovary cells.

1983 ◽  
Vol 97 (6) ◽  
pp. 1777-1787 ◽  
Author(s):  
J E Bergmann ◽  
S J Singer
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
G Protein ◽  
Rough Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Intracellular Transport ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Ovary Cells ◽  
Vesicular Stomatitis

An immunoelectron microscopic study was undertaken to survey the intracellular pathway taken by the integral membrane protein (G-protein) of vesicular stomatitis virus from its site of synthesis in the rough endoplasmic reticulum to the plasma membrane of virus-infected Chinese hamster ovary cells. Intracellular transport of the G-protein was synchronized by using a temperature-sensitive mutant of the virus (0-45). At the nonpermissive temperature (39.8 degrees C), the G-protein is synthesized in the cell infected with 0-45, but does not leave the rough endoplasmic reticulum. Upon shifting the temperature to 32 degrees C, the G-protein moves by stages to the plasma membrane. Ultrathin frozen sections of 0-45-infected cells were prepared and indirectly immunolabeled for the G-protein at different times after the temperature shift. By 3 min, the G-protein was seen at high density in saccules at one face of the Golgi apparatus. No large accumulation of G-protein-containing vesicles were observed near this entry face, but a few 50-70-mm electron-dense vesicular structures labeled for G-protein were observed that might be transfer vesicles between the rough endoplasmic reticulum and the Golgi complex. At blebbed sites on the nuclear envelope at these early times there was a suggestion that the G-protein was concentrated, these sites perhaps serving as some of the transitional elements for subsequent transfer of the G-protein from the rough endoplasmic reticulum to the Golgi complex. By 3 min after its initial asymmetric entry into the Golgi complex, the G-protein was uniformly distributed throughout all the saccules of the complex. At later times, after the G-protein left the Golgi complex and was on its way to the plasma membrane, a new class of G-protein-containing vesicles of approximately 200-nm diameter was observed that are probably involved in this stage of the transport process. These data are discussed, and the further prospects of this experimental approach are assessed.

scholarly journals Biosynthesis of the insulin receptor in rat adipose cells. Intracellular processing of the Mr-190 000 pro-receptor

1985 ◽  
Vol 232 (1) ◽  
pp. 71-78 ◽  
Author(s):  
J A Hedo ◽  
I A Simpson
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Insulin Receptor ◽  
Golgi Complex ◽  
Microsomal Fraction ◽  
Primary Cultures ◽  
Sodium Dodecyl ◽  
High Density ◽  
Low Density ◽  
Adipose Cells

We investigated the biosynthesis of the insulin receptor in primary cultures of isolated rat adipose cells. Cells were pulse-chase-labelled with [3H]mannose, and at intervals samples were homogenized. Three subcellular membrane fractions were prepared by differential centrifugation: high-density microsomal (endoplasmic-reticulum-enriched), low-density microsomal (Golgi-enriched), and plasma membranes. After detergent solubilization, the insulin receptors were immunoprecipitated with anti-receptor antibodies and analysed by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and autoradiography. After a 30 min pulse-label [3H]mannose first appeared in a band of Mr 190 000. More than 80% of the Mr-190 000 component was recovered in the microsomal fractions. Its intensity reached a maximum at 1 h in the high-density microsomal fraction and at 2 h in the low-density microsomal fraction, and thereafter declined rapidly (t 1/2 approx. 3 h) in both fractions. In the plasma-membrane fraction, the radioactivity in the major receptor subunits, of Mr 135 000 (alpha) and 95 000 (beta), rose steadily during the chase and reached a maximum at 6 h. The Mr-190 000 precursor could also be detected in the high-density microsomal fraction by affinity cross-linking to 125I-insulin. In the presence of monensin, a cationic ionophore that interferes with intracellular transport within the Golgi complex, the processing of the Mr-190 000 precursor into the alpha and beta subunits was completely inhibited. Our results suggest that the Mr-190 000 pro-receptor originates in the endoplasmic reticulum and is subsequently transferred to the Golgi complex. Maturation of the pro-receptor does not seem to be necessary for the expression of the insulin-binding site. Processing of the precursor into the mature receptor subunits appears to occur during the transfer of the pro-receptor from the Golgi complex to the plasma membrane.

scholarly journals Glycosyltransferase activities in Golgi complex and endoplasmic reticulum fractions isolated from African trypanosomes.

1984 ◽  
Vol 99 (2) ◽  
pp. 569-577 ◽  
Author(s):  
D J Grab ◽  
S Ito ◽  
U A Kara ◽  
L Rovis
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Smooth Endoplasmic Reticulum ◽  
Surface Glycoprotein ◽  
Relative Distribution ◽  
African Trypanosomes ◽  
Independent Form ◽  
Variable Surface ◽  
Dependent Form

Highly enriched Golgi complex and endoplasmic reticulum fractions were isolated from total microsomes obtained from Trypanosoma brucei, Trypanosoma congolense, and Trypanosoma vivax, and tested for glycosyltransferase activity. Purity of the fractions was assessed by electron microscopy as well as by biochemical analysis. The relative distribution of all the glycosyltransferases was remarkably similar for the three species of African trypanosomes studied. The Golgi complex fraction contained most of the galactosyltransferase activity followed by the smooth and rough endoplasmic reticulum fractions. The dolichol-dependent mannosyltransferase activities were highest for the rough endoplasmic reticulum, lower for the smooth endoplasmic reticulum, and lowest for the Golgi complex. Although the dolichol-independent form of N-acetylglucosaminyltransferase was essentially similar in all the fractions, the dolichol-dependent form of this enzyme was much higher in the endoplasmic reticulum fractions than in the Golgi complex fraction. Inhibition of this latter activity in the smooth endoplasmic reticulum fraction by tunicamycin A1 suggests that core glycosylation of the variable surface glycoprotein may occur in this organelle and not in the rough endoplasmic reticulum as previously assumed.

Morphogenèse de l'épiderme imaginal de l'abdomen de Calliphora erythrocephala (Insecte, Diptère)

Development ◽  
1978 ◽  
Vol 43 (1) ◽  
pp. 247-261
Author(s):  
Par Anne-Marie Bautz
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Rough Endoplasmic Reticulum ◽  
Cellular Proliferation ◽  
Epidermal Cells ◽  
Sensory Cells ◽  
Calliphora Erythrocephala ◽  
Abdominal Surface ◽  
Intense Activity

The morphogenesis of the abdominal epidermis in Calliphora erythrocephala begins by a cellular proliferation which proceeds slowly in larvae and rapidly in pupae. This allows histoblasts to glide and invade the whole abdominal surface. As soon as the new epidermal sheet has become continuous, differentiation begins. Generalized epidermal cells show an intense activity which leads to the deposition of imaginal cuticle from the 6th day after pupation onwards. After cuticle deposition they darken and become inactive although they remain alive, even after emergence. Trichogen and tormogen cells are even more active than generalized epidermal cells, especially the trichogen cell in which polyribosomes and microtubules are abundant. The former are possibly involved in microtubule synthesis. After cuticle deposition the trichogen and tormogen cells undergo degeneration. Their nuclei contract, rough endoplasmic reticulum breaks down and cytoplasm breaks up into fragments through infoldings which proliferate from the plasma membrane. Finally only generalized epidermal cells and sensory cells remain alive in the adult.

scholarly journals Expression of Enamel Proteins in Rough Endoplasmic Reticulum and Golgi Complex in Human Dental Germs

2017 ◽  
Vol 35 (2) ◽  
pp. 435-441
Author(s):  
Francisco Javier Gutiérrez-Cantú ◽  
Alma Lilián Guerrero-Barrera ◽  
Wulfrano Sánchez Meraz ◽  
Amaury de Jesús Pozos-Guillen ◽  
Héctor Flores-Reyes ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Enamel Proteins

scholarly journals RAB6 and microtubules restrict protein secretion to focal adhesions

2019 ◽  
Vol 218 (7) ◽  
pp. 2215-2231 ◽  
Author(s):  
Lou Fourriere ◽  
Amal Kasri ◽  
Nelly Gareil ◽  
Sabine Bardin ◽  
Hugo Bousquet ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Cell Surface ◽  
Protein Secretion ◽  
Golgi Complex ◽  
Essential Role ◽  
Focal Adhesions ◽  
Secreted Proteins ◽  
Cell Compartments ◽  
Secretion Assay

To ensure their homeostasis and sustain differentiated functions, cells continuously transport diverse cargos to various cell compartments and in particular to the cell surface. Secreted proteins are transported along intracellular routes from the endoplasmic reticulum through the Golgi complex before reaching the plasma membrane along microtubule tracks. Using a synchronized secretion assay, we report here that exocytosis does not occur randomly at the cell surface but on localized hotspots juxtaposed to focal adhesions. Although microtubules are involved, the RAB6-dependent machinery plays an essential role. We observed that, irrespective of the transported cargos, most post-Golgi carriers are positive for RAB6 and that its inactivation leads to a broad reduction of protein secretion. RAB6 may thus be a general regulator of post-Golgi secretion.

scholarly journals RADIOAUTOGRAPHIC VISUALIZATION OF THE INCORPORATION OF GALACTOSE-3H AND MANNOSE-3H BY RAT THYROIDS IN VITRO IN RELATION TO THE STAGES OF THYROGLOBULIN SYNTHESIS

1969 ◽  
Vol 43 (2) ◽  
pp. 289-311 ◽  
Author(s):  
P. Whur ◽  
Annette Herscovics ◽  
C. P. Leblond
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Golgi Apparatus ◽  
Rough Endoplasmic Reticulum ◽  
Light Microscope ◽  
Detectable Effect ◽  
Apical Vesicles ◽  
Rat Thyroid

Rat thyroid lobes incubated with mannose-3H, galactose-3H, or leucine-3H, were studied by radioautography. With leucine-3H and mannose-3H, the grain reaction observed in the light microscope is distributed diffusely over the cells at 5 min, with no reaction over the colloid. Later, the grains are concentrated towards the apex, and colloid reactions begin to appear by 2 hr. With galactose-3H, the reaction at 5 min is again restricted to the cells but it consists of clumped grains next to the nucleus. Soon after, grains are concentrated at the cell apex and colloid reactions appear in some follicles as early as 30 min. Puromycin almost totally inhibits incorporation of leucine-3H and mannose-3H, but has no detectable effect on galactose-3H incorporation during the 1st hr. Quantitation of electron microscope radioautographs shows that mannose-3H label localizes initially in the rough endoplasmic reticulum, and by 1–2 hr much of this reaction is transferred to the Golgi apparatus. At 3 hr and subsequently, significant reactions are present over apical vesicles and colloid, while the Golgi reaction declines. Label associated with galactose-3H localizes initially in the Golgi apparatus and rapidly transfers to the apical vesicles, and then to the colloid. These findings indicate that mannose incorporation into thyroglobulin precursors occurs within the rough endoplasmic reticulum; these precursors then migrate to the Golgi apparatus, where galactose incorporation takes place. The glycoprotein thus formed migrates via the apical vesicles to the colloid.

scholarly journals Cytochemical demonstration of extraperoxisomal catalase. I. Sheep liver.

1976 ◽  
Vol 24 (6) ◽  
pp. 713-724 ◽  
Author(s):  
F Roels
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Golgi Apparatus ◽  
Rough Endoplasmic Reticulum ◽  
Catalase Activity ◽  
Nonparenchymal Cells ◽  
Sheep Liver ◽  
Heat Stable ◽  
Cytochemical Demonstration ◽  
Electron Microscopes

In sheep hepatocytes catalase activity was demonstrated both within peroxisomes and within the cytosol. In the cytosol the catalase reaction product is contiguous to the plasma membrane and surrounds the nuclei, rough endoplasmic reticulum, cisternae, mitochondria and Golgi apparatus. This is the first cytochemical demonstration of guine extraperoxisomal catalase. No catalase reaction product was seen in the cytosol of nonparenchymal cells. To demonstrate catalase, both glutaraldehyde and formaldehyde fixation were used, followed by a diaminobenzidine technique modified from Novikoff and Goldfischer. Control reactions were performed to distinguish catalase reaction product from adsorption of oxidized diaminobenzidine and from precipitate due to oxidase-, peroxidase- or heat-stable peroxidatic activities. The results were evaluated in the light and electron microscopes.

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