scholarly journals Transport and topology of galactosyltransferase in endomembranes of HeLa cells.

1983 ◽  
Vol 97 (3) ◽  
pp. 723-727 ◽  
Author(s):  
G J Strous ◽  
P Van Kerkhof ◽  
R Willemsen ◽  
H J Geuze ◽  
E G Berger
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Short Pulse ◽  
Antigenic Determinants ◽  
Marker Enzyme ◽  
Uridine Diphosphate ◽  
Density Fractions ◽  
Luminal Side ◽  
Precursor Molecules

HeLa cell membranes were studied for the distribution and orientation of the Golgi marker enzyme uridine diphosphate-galactose:beta-D-N-acetylglucosamine beta, 1-4 transferase (GT). Short pulse labeling in the presence of [35S]methionine resulted in two precursor species (Mr = 44,000 and 47,000), present in a microsomal fraction with a density of 1.18 g/ml in sucrose, presumably derived from the rough endoplasmic reticulum. Processing of the N-linked oligosaccharide(s) occurred only after the precursor molecules migrated to lighter density fractions, presumably derived from the Golgi complex. The mature GT molecules (Mr = 54,000) contain O-linked oligosaccharides as shown by beta-elimination of metabolically incorporated [3H]galactose. The O-glycosylation occurred mainly in the light density fractions. The topology of GT was studied on membrane fractions after labeling with [35S]methionine as well as immunocytochemically on ultrathin cryosections at the electron microscope level. Our results indicate that both the antigenic determinants of GT as well as polypeptide chain are present intramembraneously and at the luminal side of the membranes of the Golgi complex and rough endoplasmic reticulum.

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.

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 Biosynthesis of lipoprotein: location of nascent apoAI and apoB in the rough endoplasmic reticulum of chicken hepatocytes

1992 ◽  
Vol 117 (6) ◽  
pp. 1161-1169 ◽  
Author(s):  
JL Dixon ◽  
R Chattapadhyay ◽  
T Huima ◽  
CM Redman ◽  
D Banerjee
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Microscopic Examination ◽  
Microsomal Membrane ◽  
Golgi Cell ◽  
Lipoprotein Particles ◽  
Morphological Findings ◽  
Cytoplasmic Surface ◽  
Luminal Side ◽  
Cell Fractions

Our previous studies showed that in hepatic RER of young chickens, nascent apoAI is not associated with lipoprotein particles and only becomes part of these lipoprotein structures in the Golgi. In this study, we have used three different methodologies to determine the locations of apoAI and apoB in the RER and compared them to that of albumin. Immunoelectron microscopic examination of the RER cell fractions showed that both apoAI and apoB were associated only with the RER membrane whereas albumin was located both within the lumen and on the limiting membrane of the vesicles. To examine the possibility of membrane integration of nascent apoAI and apoB in the RER, we administered L-[3H]leucine to young chickens for 10 min, isolated RER, treated this cell fraction with buffers of varying pH, and measured the release of radioactive albumin, apoAI, and apoB. The majority of nascent apoAI (64%), nascent apoB (100%), and nascent albumin (97%) was released from RER vesicles at pH 11.2, suggesting that, like albumin, apolipoproteins are not integrated within the membrane. To determine if nascent apoproteins are exposed to the cytoplasmic surface, we administered L-[3H]leucine to young chickens and at various times isolated RER and Golgi cell fractions. Radioactive RER and Golgi cell fractions were treated with exogenous protease and the percent of nascent apoAI and apoB accessible to proteolysis was determined and compared to that of albumin. At 5, 10, and 20 min of labeling, 35-56% of nascent apoAI and 60-75% of apoB in RER were degraded, while albumin was refractive to this treatment. At all times both apolipoproteins and albumin present in Golgi cell fractions were protected from proteolysis. These biochemical and morphological findings indicate that apoAI and apoB are associated with the rough microsomal membrane and are partially exposed to the cytoplasmic surface at early stages of secretion. They may later enter the luminal side of the ER and, on entering the Golgi, form lipoprotein particles.

scholarly journals The beads in the Golgi complex-endoplasmic reticulum region.

1976 ◽  
Vol 70 (2) ◽  
pp. 384-394 ◽  
Author(s):  
M Locke ◽  
P Huie
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Insect Cell ◽  
Cell Types ◽  
Feulgen Staining ◽  
Clear Halo ◽  
Bismuth Salts ◽  
Transition Vesicles

The region between the rough endoplasmic reticulum (ER) and the Golgi complex has been studied in a variety of insect cell types in an attempt to find a marker for the exit gate or gates from the ER. We have found that the smooth surface of the rough endoplasmic reticulum near Golgi complex transitional elements has beadlike structures arranged in rings at the base of transition vesicles. They occur in all insect cell types and a variety of other organisms. The beads can be seen only after staining in bismuth salts. They are 10-12 nm in diameter and are separated from the membrane and one another by a clear halo giving them a center to center spacing of about 27 nm. The beads are not sensitive to nucleases under conditions which disrupt ribosomes or remove all Feulgen staining material from the nucleus. Under conditions similar to those used to stain tissue, bismuth does not react in vitro with nucleic acids. The component of the beads that stains preferentially with bismuth is therefore probably not nucleic acid.

Localization of Alkaline Phosphatase in Marrow Cells

1973 ◽  
Vol 31 ◽  
pp. 692-693
Author(s):  
Anne D. Geddes ◽  
Mary E. Kirchen ◽  
G. June Marshall
Keyword(s):  
Alkaline Phosphatase ◽  
Endoplasmic Reticulum ◽  
Light Microscopy ◽  
Rough Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Significant Marker ◽  
Leukocyte Alkaline Phosphatase ◽  
Marrow Cells

Leukocyte alkaline phosphatase(LAP) is potentially a significant marker for following the maturation sequence of normal and abnormal neutrophils. This enzyme can be localized in the rough endoplasmic reticulum (rer) and in the Golgi complex of immature neutrophils but it has been very difficult to demonstrate LAP activity in the granules of mature neutrophils. This observation presents a dilemma since LAP is present in higher concentrations in mature as opposed to immature neutrophils as demonstrated by biochemical and light microscopy methods.In an attempt to solve this problem, variations on the routine methods for demonstrating LAP activity were explored. Acetone, formaldehyde, methanol and gluteraldehyde were used as fixatives.

scholarly journals Subcellular localization of complex carbohydrates in rat macrophages and monocytes.

1979 ◽  
Vol 27 (8) ◽  
pp. 1180-1181 ◽  
Author(s):  
P L Sannes ◽  
M Eguchi ◽  
S S Spicer
Keyword(s):  
Bone Marrow ◽  
Endoplasmic Reticulum ◽  
Subcellular Localization ◽  
Rough Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Peripheral Blood ◽  
Periodic Acid ◽  
High Iron ◽  
Cytoplasmic Vesicles ◽  
Complex Carbohydrates

Methods for visualization of complex carbohydrates ultrastructurally were employed to study specific organelles of the rat monocyte and macrophage. Vicinal glycols of glycoconjugates were demonstrated with the periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) postembedding sequence and acid groups were delineated by the dialyzed iron (DI) and high iron diamine (HID) preembedding techniques. Lysosomal bodies were generally found reactive with all three methods, although those of monocytes from the bone marrow and peripheral blood were notably lacking in acidic groups. The Golgi complex was consistently PA-TCH-SP-reactive, as were associated vesicles and occasional cisternal expansions, possibly related to GERL. Numerous cytoplasmic vesicles and small granulated structures and cisternae of the rough endoplasmic reticulum were also PA-TCH-SP-reactive.

scholarly journals Two fractions of rough endoplasmic reticulum from rat liver. I. Recovery of rapidly sedimenting endoplasmic reticulum in association with mitochondria.

1977 ◽  
Vol 72 (3) ◽  
pp. 714-725 ◽  
Author(s):  
G C Shore ◽  
J R Tata
Keyword(s):  
Endoplasmic Reticulum ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Rat Liver ◽  
Rough Endoplasmic Reticulum ◽  
Structural Damage ◽  
Gradient Centrifugation ◽  
Mitochondrial Protein ◽  
Enzyme Analysis ◽  
Marker Enzyme

Low-speed centrifugation (640 g) of rat liver homogenates, prepared with a standard ionic medium, yielded a pellet from which a rapidly sedimenting fraction of rough endoplasmic reticulum (RSER) was recovered free of nuclei. This fraction contained 20-25% of cellular RNA and approximately 30% of total glucose-6-phosphatase (ER marker) activity. A major portion of total cytochrome c oxidase (mitochondrial marker) activity was also recovered in this fraction, with the remainder sedimenting between 640 and 6,000 g. Evidence is provided which indicates that RSER may be intimately associated with mitochondria. Complete dissociation of ER from mitochondria in the RSER fraction required very harsh conditions. Sucrose density gradient centrifugation analysis revealed that 95% dissociation could be achieved when the RSER fraction was first resuspended in buffer containing 500 mM KCl and 20 mM EDTA, and subjected to shearing. Excluding KCl, EDTA, or shearing from the procedure resulted in incomplete separation. Both electron microscopy and marker enzyme analysis of mitochondria purified by this procedure indicated that some structural damage and leakage of proteins from matrix and intermembrane compartments had occurred. Nevertheless, when mitochondria from RSER and postnuclear 6,000-g pellet fractions were purified in this way fromanimals injected with [35S]methionine +/- cycloheximide, mitochondria from the postnuclear 6,000-g pellet were found to incorporate approximately two times more cytoplasmically synthesized radioactive protein per milligram mitochondrial protein (or per unit cytochrome c oxidase activity) than did mitochondria from the RSER fraction. Mitochondria-RSER associations, therefore, do not appear to facilitate enhanced incorporation of mitochondrial proteins which are newly synthesized in the cytoplasm.

scholarly journals The mystery of the unstained Golgi complex cisternae.

1983 ◽  
Vol 31 (8) ◽  
pp. 1019-1032 ◽  
Author(s):  
M Locke ◽  
P Huie
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Secretory Pathway ◽  
Secretory Vesicles ◽  
Transition Vesicles

The Champy-Maillet OsKI reaction has been used upon Golgi complexes to show two kinds of staining. It stains material being processed as it passes along the secretory pathway of the rough endoplasmic reticulum (RER) and Golgi cisternae (GC) up to crystallization in secretory vesicles. It also stains separately the environment within parts of the GC. This GC staining may occur in all compartments (transition vesicles, saccules, condensing vacuoles), but it is characteristically missing from any one of them. The unstained cisternae may be explained if outer saccules are made from either stained or unstained transition vesicles, both of which occur. The presence of empty, unstained transition vesicles is dictated by the surface to volume ratios of microvesicles in relation to saccules. Most transition vesicles must return their membrane to the endoplasmic reticulum, but from time to time it is presumed that they fuse to make a saccule. Saccules, stained and unstained, then mature through the stack. OsKI reactions with tissues and test molecules suggest that in the RER and GC the stain detects labile--S . S--bridges before they lock the tertiary configuration of proteins.

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