An interaction between brain microtubules and smooth endoplasmic reticulum in vitro

1982 ◽  
Vol 10 (1) ◽  
pp. 58-58
Author(s):  
ALAN J. HARGREAVES ◽  
W. GRAHAM McLEAN
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Brain Microtubules

In Vitro Induction of Crystals of MT Protein by Vinblastine-Colcemid in Mouse Spermatids

1974 ◽  
Vol 32 ◽  
pp. 132-133
Author(s):  
John J. Wolosewick ◽  
John H. D. Bryan
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Nuclear Ring ◽  
Rough Er ◽  
Distal Direction ◽  
In Vitro Induction

Early in spermiogenesis the manchette is rapidly assembled in a distal direction from the nuclear-ring-densities. The association of vesicles of smooth endoplasmic reticulum (SER) and the manchette microtubules (MTS) has been reported. In the mouse, osmophilic densities at the distal ends of the manchette are the organizing centers (MTOCS), and are associated with the SER. Rapid MT assembly and the lack of rough ER suggests that there is an existing pool of MT protein. Colcemid potentiates the reaction of vinblastine with tubulin and was used in this investigation to detect this protein.

scholarly journals High-affinity binding of glycogen-synthase phosphatase to glycogen particles in the liver. Role of glycogen in the inhibition of synthase phosphatase by phosphorylase a

1987 ◽  
Vol 246 (2) ◽  
pp. 367-374 ◽  
Author(s):  
L Mvumbi ◽  
W Stalmans
Keyword(s):  
Endoplasmic Reticulum ◽  
High Speed ◽  
Glycogen Synthase ◽  
Smooth Endoplasmic Reticulum ◽  
Active Form ◽  
Glycogen Concentration ◽  
High Affinity ◽  
Glycogen Particles

1. Post-mitochondrial supernatants were prepared from the livers of 24 h-fasted rats. Upon centrifugation at high speed, the major part of the glycogen-synthase phosphatase activity sedimented with the microsomal fraction. However, two approaches showed that the enzyme was associated with residual glycogen rather than with vesicles of the endoplasmic reticulum. Indeed, the activity was entirely solubilized when the remaining glycogen was degraded either by glucagon treatment in vivo or by alpha-amylolysis in vitro. No evidence could be found for an association of glycogen-synthase phosphatase with the smooth endoplasmic reticulum, as isolated with the use of discontinuous sucrose gradients. 2. After solubilization by glucagon treatment in vivo, synthase phosphatase could be transferred to glycogen particles with very high affinity. Half-maximal binding occurred at a glycogen concentration of about 0.25 mg/ml, whereas glycogen synthase and phosphorylase required 1.5-2 mg/ml. 3. In gel-filtered extracts prepared from glycogen-depleted livers, the activation of glycogen synthase was not inhibited at all by phosphorylase alpha. The inhibition was restored when the liver homogenates were prepared in a glycogen-containing buffer. The effect was half-maximal at a glycogen concentration of about 0.25 mg/ml, and virtually complete at 1 mg/ml. These findings explain long-standing observations that in fasted animals the liver contains appreciable amounts of both synthase and phosphorylase in the active form.

scholarly journals Polyribosomal attachment to rat liver and hepatoma endoplasmic reticulum in vitro. A method for its study

1971 ◽  
Vol 121 (2) ◽  
pp. 271-278 ◽  
Author(s):  
W. L. Ragland ◽  
T. K. Shires ◽  
H. C. Pitot
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Citric Acid ◽  
Low Temperature ◽  
Rough Endoplasmic Reticulum ◽  
Half Life ◽  
Binding Capacity ◽  
Smooth Endoplasmic Reticulum ◽  
Quantitative Separation

A system for study and measurement of the attachment in vitro of exogenous polyribosomes to membranes has been presented. Its main features are use of low temperature, post-microsomal supernatant, pyrophosphate and citric acid to remove ribosomes from the surface of rough endoplasmic reticulum, and a method for quantitative separation of unattached from membrane-associated polyribosomes. The following were found. (1) Rough endoplasmic reticulum, from which ribosomes had been removed by treatment with pyrophosphate and citrate, bound over 50% of added polyribosomes, whereas the untreated (or control) rough and smooth endoplasmic reticulum and the smooth endoplasmic reticulum treated with pyrophosphate–citrate did not bind polyribosomes. (2) The polyribosome-binding capacity of rough endoplasmic reticulum stripped of its ribosomes decayed upon storage of the membranes at 0–4°C. The half-life of this decay was about 6 days whereas that of the polyribosome-binding capacity of hepatoma stripped rough endoplasmic reticulum was about 1.5 days. (3) Preparations of stripped rough endoplasmic reticulum after reassociation with polyribosomes in vitro were quite similar to preparations of native rough endoplasmic reticulum as viewed with the electron microscope. Evidence is presented to support the contention that association of polyribosomes with membranes was the result of polyribosomal reattachment to the membranes rather than trapping of the polyribosomes between vesicles of the membranes.

scholarly journals The submicrosomal localization of acyl-coenzyme A–cholesterol acyltransferase and its substrate, and of cholesteryl esters in rat liver

1978 ◽  
Vol 174 (3) ◽  
pp. 863-872 ◽  
Author(s):  
Santhirasegaram Balasubramaniam ◽  
Soundararajan Venkatesan ◽  
Konstantinos A. Mitropoulos ◽  
Timothy J. Peters
Keyword(s):  
Endoplasmic Reticulum ◽  
Rat Liver ◽  
Plasma Membranes ◽  
Microsomal Fraction ◽  
Smooth Endoplasmic Reticulum ◽  
Cholesterol Acyltransferase ◽  
Specific Radioactivity ◽  
Cholesteryl Esters ◽  
Distribution Profile

To determine the submicrosomal distribution of acyl-CoA–cholesterol acyltransferase and of cholesteryl esters, the microsomal fraction and the digitonin-treated microsomal preparation of rat liver were subjected to analytical centrifugation on sucrose density gradients. With untreated microsomal fractions the distribution profile and the median density of acyl-CoA–cholesterol acyltransferase were very similar to those of RNA. This is in contrast with hydroxymethylglutaryl-CoA reductase and cholesterol 7α-hydroxylase, which are confined to endoplasmic reticulum membranes with low ribosomal coating. In digitonin-treated microsomal preparations activity of acyl-CoA–cholesterol acyltransferase was not detectable. The labelling of untreated microsomal fractions with trace amounts of [14C]cholesterol followed by subfractionation of the labelled microsomal fraction showed that the specific radioactivity of cholesteryl esters obtained in vitro by the various subfractions was similar with all subfractions but different from the specific radioactivity of the 7α-hydroxycholesterol obtained in vitro by the same subfraction. These results demonstrate the existence of two pools of cholesterol confined to membranes from the endoplasmic reticulum, one acting as substrate for cholesterol 7α-hydroxylase and the other acting as substrate for acyl-CoA–cholesterol acyltransferase. The major part of cholesteryl esters present in both untreated and digitonin-treated microsomal fractions was distributed at densities similar to those of membranes from the smooth endoplasmic reticulum and at densities lower than those of smooth membranes from Golgi apparatus. The ratio of the concentrations of non-esterified to esterified cholesterol in the subfractions from both untreated and digitonin-treated microsomal fractions was highest at the maximum distribution of plasma membranes.

NSP-encoded reticulons, neuroendocrine proteins of a novel gene family associated with membranes of the endoplasmic reticulum

1994 ◽  
Vol 107 (9) ◽  
pp. 2403-2416 ◽  
Author(s):  
H.J. van de Velde ◽  
A.J. Roebroek ◽  
N.H. Senden ◽  
F.C. Ramaekers ◽  
W.J. Van de Ven
Keyword(s):  
Amino Acids ◽  
Endoplasmic Reticulum ◽  
Gene Family ◽  
Biochemical Characterization ◽  
Smooth Endoplasmic Reticulum ◽  
Dendritic Tree ◽  
Cell Types ◽  
In Vitro Translation ◽  
Amino Terminal

The novel NSP gene was previously shown to encode, among a variety of neuroendocrine cell types, two 3′-overlapping transcripts, a 3.4 kb one for NSP-A (776 amino acids) and a 1.8 kb one for NSP-C (208 amino acids). The deduced proteins, which were predicted to possess distinct amino-terminal regions, appeared to exhibit some architectural resemblance to known neuroendocrine proteins. In this paper the biochemical characterization and subcellular localization of the two proteins is addressed. In vitro translation of NSP-A and -C RNA produced proteins of about 135 and 23 kDa, respectively. Proteins of similar molecular mass were also detected in immunoprecipitation and western blot analyses of neural and endocrine cells using specific anti-NSP-A or -C antisera; some heterogeneity of NSP-A was observed. NSP-A, but not NSP-C, appeared to be highly phosphorylated and preferentially on serine residues. In immunocytochemical studies, we demonstrated that NSP-A and -C are associated with the endoplasmic reticulum; NSP-A was found to co-localize with SERCA2b, a membrane-associated Ca(2+)-ATPase of the endoplasmic reticulum. In Purkinje cells, we found NSP-immunostaining in the perikaryon, the extensive dendritic tree and the axon, also suggesting association with the smooth endoplasmic reticulum. Biochemical studies of NSP-A provided evidence that NSP-A is strongly associated with microsomal membranes and analysis of deletion mutants of NSP-A revealed that the hydrophobic carboxy-terminal portion of the protein, which is also present in NSP-C, is critical for membrane binding. Through database searches, finally, we found two different NSP-related sequences, one in a sequenced region of human chromosome 19, and the second in a human, pancreatic islet-derived partial cDNA, suggesting that the NSP gene is the prototype of a larger gene family. The results of our studies seem to indicate that the NSP-encoded proteins are novel, membrane-anchored components of the endoplasmic reticulum for which we propose the name reticulons.

scholarly journals The impact of Alpha/ESHRE consensus regarding oocytes with aggregates of smooth endoplasmic reticulum (SERa) on in vitro fertilization outcome

2015 ◽  
Vol 32 (11) ◽  
pp. 1629-1635 ◽  
Author(s):  
Liliana Restelli ◽  
Silvia Delle Noci ◽  
Alice Mangiarini ◽  
Stefania Ferrari ◽  
Edgardo Somigliana ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
In Vitro Fertilization ◽  
Smooth Endoplasmic Reticulum ◽  
Vitro Fertilization ◽  
The Impact

scholarly journals Live birth rates in In vitro fertilization cycles with oocytes containing smooth endoplasmic reticulum aggregates and normal oocytes

2019 ◽  
Vol 12 (2) ◽  
pp. 156
Author(s):  
Sumana Gurunath ◽  
Reeta Biliangady ◽  
UmaMaheshwari Sundhararaj ◽  
Ambika Gangadharswamy ◽  
Swathi Gundlapalli ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
In Vitro Fertilization ◽  
Live Birth ◽  
Smooth Endoplasmic Reticulum ◽  
Birth Rates ◽  
Vitro Fertilization ◽  
Live Birth Rates

Cryohomogenization of liver to make in vitro preparations of rough endoplasmic reticulum and other organelles

1996 ◽  
Vol 54 ◽  
pp. 912-913
Author(s):  
A. Kent Christensen
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Microsomal Fraction ◽  
Biochemical Study ◽  
Smooth Endoplasmic Reticulum ◽  
Cell Fractionation ◽  
Fresh Tissue ◽  
Common Fractions ◽  
The Common

Cell fractionation has been used for many years to isolate organelles for biochemical study. Typically, fresh tissue is homogenized in a suitable buffer, and the various size-classes of organelles are then isolated by differential centrifugation. One of the common fractions is the microsomal fraction, which consists largely of vesiculated rough and smooth endoplasmic reticulum, and of Golgi elements.In the past we have investigated bound polysomes on the rough endoplasmic reticulum (RER) by electron microscopy, and have used cell fractionation and EM to study the orientation of ribosomes in polysomes bound to rough microsomal vesicles. However, the value of the cell fractionation material in our work has been limited by the small size of the microsomal vesicles, which are produced by vesicular fragmentation of the endoplasmic reticulum during tissue homogenization. For our work we need in vitro preparations in which the RER retains its cisternal form, rather than being fragmented into small vesicles. This report describes a method we have devised that can yield relatively intact RER in vitro.

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