A possible structural basis for the extracellular release of acetylcholinesterase

1975 ◽  
Vol 191 (1103) ◽  
pp. 271-283 ◽  
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Chromaffin Cells ◽  
Plasma Membranes ◽  
Cholinesterase Activity ◽  
Smooth Endoplasmic Reticulum ◽  
Splanchnic Nerve ◽  
Ultrastructural Localization ◽  
Acetylcholinesterase Activity ◽  
Structural Basis

The ultrastructural localization of acetylcholinesterase and non-specific cholinesterase activity has been studied in sections of ox adrenal medulla by cytochemical methods. Non-specific cholinesterase activity, identified by using butyrylthiocholine as substrate and ethopropazine as inhibitor, occurs intracellularly in some adrenaline-containing chromaffin cells: the reaction end-product is deposited within the cisternae of the endoplasmic reticulum and in the nuclear envelope. Reaction end-product of non-specific cholinesterase also occurs in the endoplasmic reticulum of pericytes, around sinusoids and capillaries and within smooth muscle cells. Acetylcholinesterase activity, identified by using acetylthiocholine as substrate and BW 284C51 as inhibitor, occurs in both the splanchnic nerve and in chromaffin cells. Reaction end-product is found at the following sites (i) around myelinated and unmyelinated non-terminal axons of splanchnic nerve, between the axolemma and the Schwann cell membrane; (ii) within the cisternae of axonal smooth endoplasmic reticulum; sometimes these cisternae appear to be connected to the axolemma; (iii) between the axolemmas of preterminal axons and the plasma membranes of chromaffin cells; (iv) between the axolemmas of nerve terminals and the plasma membranes of chromaffin cells, including the synaptic cleft; (v) within cisternae of rough and smooth endoplasmic reticulum, and also within the nuclear envelope, of both adrenaline- and noradrenaline-containing chromaffin cells; (vi) between the plasma membranes of adjacent chromaffin cells, but only when one or both of these cells contain reaction product within the cisternae of its endoplasmic reticulum; these cisternae sometimes appear to be connected to the plasma membrane. These observations raise the question whether the acetylcholinesterase activity released from the perfused adrenal gland might originate from the cisternae of the endoplasmic reticula of splanchnic nerve and/or chromaffin cell.

scholarly journals ULTRASTRUCTURAL LOCALIZATION OF CHOLINESTERASE ACTIVITY IN THE DEVELOPING RAT RETINA

1974 ◽  
Vol 22 (9) ◽  
pp. 868-880 ◽  
Author(s):  
ARTHUR W. SPIRA
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Cholinesterase Activity ◽  
Ganglion Cells ◽  
Plexiform Layer ◽  
Ultrastructural Localization ◽  
Acetylcholinesterase Activity ◽  
Inner Plexiform Layer ◽  
Cholinesterase Activities ◽  
Developing Rat

Retinae of rats from the 16th day of gestation to 10 weeks postnatal age were treated for the ultrastructural localization of cholinesterases according to the method of Lewis and Shute. The use of selective inhibitors served to differentiate between acetylcholinesterase and nonspecific cholinesterase activities. Nonspecific cholinesterase activity was marked in the rough endoplasmic reticulum of pigmented epithelium but only during the 1st 2 postnatal weeks. Acetylcholinesterase activity was prominent (a) in the rough endoplasmic reticulum, nuclear envelope and Golgi apparatus of ganglion cells in fetal and mature retinae; (b) transiently, between processes in the outer plexiform layer and in the perikarya of some horizontal cells; and (c) between processes in the inner plexiform layer coincident with the appearance of synapses, as well as in the mature retina. These localizations are suggestive of an association between cholinesterases and early stages of photoreceptor segment formation and consistent with a function in plexiform layer maturation and synaptic transmission in the inner plexiform layer.

HISTOCHEMICALLY DEMONSTRABLE CHOLINESTERASES IN THE ADRENAL MEDULLA OF THE HAMSTER AND THE EFFECT OF DENERVATION

1962 ◽  
Vol 39 (2) ◽  
pp. 288-293 ◽  
Author(s):  
O. Eränkö ◽  
V. Hopsu ◽  
A. Palkama
Keyword(s):  
Adrenal Medulla ◽  
Cholinesterase Activity ◽  
Splanchnic Nerve ◽  
Acetylcholinesterase Activity ◽  
Nerve Fibres

ABSTRACT Acetylcholinesterase and non-specific cholinesterase gave positive histochemical reactions in the nerve fibres of the adrenal medulla of the hamster. Acetylcholinesterase activity was also observed in the fine nervous network covering the whole medulla, while non-specific cholinesterase activity was limited to fewer fibres. Division of the splanchnic nerve did not essentially affect the non-specific cholinesterase reaction but abolished most of the acetylcholinesterase activity. However, some fibres both in the cortex and in the medulla retained their acetylcholinesterase activity after denervation.

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 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.

Les systèmes membranaires de Scopulariopsis brevicaulis. II. Étude comparée de leur composition lipidique

1987 ◽  
Vol 33 (1) ◽  
pp. 78-81 ◽  
Author(s):  
Jean-Louis Fonvieille ◽  
Jane-Marie Touze-Soulet ◽  
Charles Montant
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membranes ◽  
Smooth Endoplasmic Reticulum ◽  
Gradient Centrifugation ◽  
Percoll Gradient ◽  
Mitochondrial Membranes ◽  
Isolation Method ◽  
Discontinuous Sucrose Gradient ◽  
Phospholipid Ratio ◽  
Scopulariopsis Brevicaulis

Biochemical studies of Scopulariopsis brevicaulis membranes (except mitochondrial membranes), in particular their lipid composition, were undertaken using plasma membranes and fractions containing smooth endoplasmic reticulum and Golgi apparatus membranes. The results obtained by two separation techniques, a continuous Percoll gradient and a discontinuous sucrose gradient centrifugation, were similar. Depending on the isolation method used, the plasma membrane contained 30 or 33% protein and 23 or 30% lipid of which 16.5 or 18% was phospholipid. The sterol/phospholipid ratio was 1.98 or 2.28. The endoplasmic reticulum + Golgi fraction contained 21 or 26.7% protein and 43 or 50% lipid of which 7 or 10% was phospholipid. The sterol/phospholipid ratio was 0.85 or 0.81.

The fine structure of fertilization in the fern Marsilea vestita

1978 ◽  
Vol 30 (1) ◽  
pp. 265-281
Author(s):  
D.G. Myles
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Nuclear Envelope ◽  
Plasma Membranes ◽  
Multilayered Structure ◽  
Thick Wall ◽  
Clear Space ◽  
Marsilea Vestita ◽  
Sperm Plasma Membrane ◽  
Sperm Penetration

The ultrastructural details of fertilization in the fern Marsilea vestita, including gamete approach and fusion, the fate of the spermatozoid organelles and the development of a possible block to polyspermy are described. The spermatozoid approaches the egg through layers of mucilage that surround the megaspores. It moves down the neck of the archegonium into the cavity above the egg. In order to reach the egg, it must move through a small hole in the thick wall that lies across the top of the egg. The fusion of the plasma membranes of the gametes results in an outflow of egg cytoplasm into the clear space under the sperm plasma membrane, creating a fertilization cone. All the organelles of the fertilizing spermatozoid, including nucleus, mitochondrion, microtubule ribbon, multilayered structure, and flagellar band, with approximately 150 flagella, enter the egg cytoplasm. The nucleus enters as a condensed rod of chromatin with no nuclear envelope. The chromatin begins to disperse immediately and a new nuclear envelope is formed around the chromatin by egg endoplasmic reticulum. The mitochondrion and the microtubules of the ribbon and flagella are broken down, but the fates of the flagellar band and the multilayered structure have not been determined. After spermatozoid penetration, a new extracellular layer appears above the surface of the egg, beginning in the region of sperm penetration and spreading across the top of the egg. This layer may be important in preventing other spermatozoids from fusing with the egg.

scholarly journals Intracellular labeling with ferritin conjugates. A specificity problem due to the affinity of unconjugated ferritin for selected intracellular sites.

1979 ◽  
Vol 27 (7) ◽  
pp. 1095-1102 ◽  
Author(s):  
E L Parr
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Nuclear Envelope ◽  
Phosphate Buffer ◽  
Plasma Membranes ◽  
Cell Types ◽  
Purification Procedure ◽  
Nonspecific Binding ◽  
Wide Range ◽  
Antibody Conjugates

Nonspecific binding of ferritin to chromatin and the cytoplasmic aspect of the nuclear envelope was observed when nonantigenic, serum-washed hepatocyte nuclei were incubated in ferritin-antibody conjugates. This labeling was duplicated when nuclei from a wide range of species and cell types were exposed to unconjugated ferritin. Unconjugated ferritin binding to nuclei did not depend on a subpopulation of denatured molecules or on the ferritin purification procedure. Binding occurred equally on unfixed and formaldehyde-fixed nuclei, but no ferritin bound to glutaraldehyde-fixed nuclei. Inconjugated ferritin also bound to the cytoplasmic aspects of the rough endoplasmic reticulum and the plasma membrane. The tracer did not bind to lysosomes, mitochondria, Golgi vesicles, the extracellular surface of plasma membranes, or the intracisternal surfaces of ruptured nuclear envelopes. The addition of 0.4 M KCl or 0.7 M NaCl to ferritin solutions and washing media at neutral pH reduced the binding of conjugated and unconjugated ferritin to nuclei to about 3% of that seen in 0.10 M phosphate buffer alone. The added salts caused little extraction of nuclear contents from formaldehyde-fixed nuclei. The use of one of these salts in ferritin conjugates should considerably improve the specificity of intracellular labeling.

scholarly journals Retention of membrane proteins by the endoplasmic reticulum.

1985 ◽  
Vol 101 (5) ◽  
pp. 1724-1732 ◽  
Author(s):  
R Brands ◽  
M D Snider ◽  
Y Hino ◽  
S S Park ◽  
H V Gelboin ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Monoclonal Antibody ◽  
Endoplasmic Reticulum ◽  
Cytochrome P450 ◽  
Membrane Proteins ◽  
Nuclear Envelope ◽  
Smooth Endoplasmic Reticulum ◽  
Membrane Glycoprotein ◽  
Glucosidase Ii ◽  
Er Membrane

We have used a monoclonal antibody specific for a hydrocarbon-induced cytochrome P450 to localize, by electron microscopy, the epitope-specific cytochrome P450. The cytochrome was found in the rough and smooth endoplasmic reticulum (ER) and the nuclear envelope of hepatocytes. Significant quantities of cytochrome P450 were not found in Golgi stacks. We also could not find any evidence of Golgi-associated processing of the Asn-linked oligosaccharide chains of two well-characterized ER membrane glycoprotein enzymes (glucosidase II and hexose-6-phosphate dehydrogenase), or of the oligosaccharides attached to the bulk of the glycoproteins of the ER membrane. We conclude that these ER membrane proteins are efficiently retained during a process of highly selective export from this organelle.

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