Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.1.7 (acetylcholinesterase)
28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Studies were carried out on the polymorphism of acetylcholinesterase (AChE, EC 3.1.1.7) in a neuroblastoma x sympathetic ganglion cell hybrid cell line (T28) and its parental clone (N18TG2). These cells contain the tetrameric (G4, 10S), dimeric (G2, 6.5S) and monomeric (G1, 4S) forms of AchE, but not the collagen-tailed A12(16S) form of the sympathetic ganglion. Three variants of these forms could be distinguished on the basis of their solubility properties: (i) secreted forms which do not interact with the detergent Triton X-100; (ii) cellular forms which may be solubilized in detergent-free buffer and which interact reversibly with Triton X-100; (iii) cellular forms which require detergent for solubility, and aggregate in its absence. By using a nonpenetrating inhibitor, we demonstrated that, in T28 stationary cells, the cellular G4 form is associated with the plasma membrane, whereas the G1 form is intracellular. During induction of AChE activity in T28 cells, the relative proportion of the G4 form increases, suggesting, in agreement with previous observations, that G1 is a metabolic precursor of G4. The evolution of AChE molecular forms released into the culture medium closely resembles that of the cellular forms. The preferential accumulation of the G4 molecules does not simply depend on the cellular level of G1. It is favoured by culture conditions which promote morphological differentiation, but does not require the actual extension of neurites. T28 cells as well as other neuroblastoma-derived cells appear to be useful experimental materials to investigate the regulatory mechanisms underlying the maturation of AChE globular forms.
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PMID:Modulation of the distribution of acetylcholinesterase molecular forms in a murine neuroblastoma x sympathetic ganglion cell hybrid cell line. 745 5

Electroplax tissue from Torpedo californica contains two major structural forms of the enzyme acetylcholinesterase. One form, composed of tetrameric protomers which are further aggregated by interactions among associated collagenous "tail fibers", has been well characterized previously. This form is associated in situ with the basal lamina. The other form is described and characterized herein. This latter form accounts for at least 50% of the acetylcholinesterase activity of the tissue. This enzyme associated with the tissue phospholipids. It aggregates in aqueous solution but readily dissociates to dimers in 1% sodium cholate solution, a solvent in which it is both soluble and catalytically fully active. The same dimer is obtained in sodium dodecyl sulfate solution where the enzyme is denatured. Denaturation in the presence of the reductant dithiothreitol results in the formation of a single 80000-dalton subunit. The purified enzyme contains no collagenous component. It is not derivable from the collagenous "tailed-enzyme" form in the tissue homogenate. However, the two enzymes have similar molecular weight catalytic subunits and the same substrate-dependent turnover numbers (per active site) for a variety of choline esters which are generally utilized to distinguish specific esterase function. In the tissue homogenate each form of the enzyme is associated with a characteristic structural component (phospholipid or collagen). By implication, acetylcholinesterase function is localized in situ in the phospholipid membrane as well as at the basal lamina.
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PMID:Major component of acetylcholinesterase in Torpedo electroplax is not basal lamina associated. 745 21

Muscle biopsies from three patients with cardiomyopathy, mental retardation and increased serum creatine kinase levels revealed scattered fibers with tiny intracytoplasmic vacuoles containing basophilic and acid phosphatase-positive material and slightly increased amounts of PAS-positive granules. These findings are consistent with those seen in the so-called lysosomal glycogen storage disease with normal acid maltase. In addition to the vacuoles, there were occasional folds or indentations in the sarcolemma which were connected to the membrane enclosing the vacuoles. These membranes were well demonstrated histochemically by the nonspecific esterase and acetylcholinesterase stains. On electron microscopy, most of the vacuoles were bounded by membranes with basal lamina. The vacuolar membrane stained positively with antibodies raised to dystrophin, dystrophin-associated glycoproteins, laminin and type 4 collagen, and it was identical to the sarcolemma and its basal lamina. Therefore, the membrane abnormality which causes sarcolemmal folding is probably critical to understanding the pathomechanism of this disease.
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PMID:Sarcolemmal indentation in cardiomyopathy with mental retardation and vacuolar myopathy. 753 16

Asymmetric acetylcholinesterase (AChE) contains three tetrameric sets of catalytic subunits disulfide-linked to structural subunits of a collagenic tail. This form is localized in the basement membrane zone of the neuromuscular junction, where it interacts with proteoglycans. It has been described that heparin-binding domains of many proteins contains clusters of basic residues. Here we show that protamine--a highly basic protein--specifically solubilizes asymmetric AChE from the rat neuromuscular junction, starting at 25 micrograms/ml and reaching a plateau at 250 micrograms/ml protamine. We also show that protamine was able to displace AChE bound to heparin-agarose. Two synthetic peptides corresponding to the sequence of the collagenic tail polypeptide also release the enzyme. Finally, we propose that two heparin-binding consensus sequences (-B-B-X-B-) are present in the tail of AChE. Our results indicate that clusters of basic residues are responsible for the interaction of the collagen-tailed AChE with proteoglycans.
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PMID:Effect of protamine on the solubilization of collagen-tailed acetylcholinesterase: potential heparin-binding consensus sequences in the tail of the enzyme. 754 66

1. The electrocytes from the electric organ of the Patagonian ray P. extenta are very unusual cells: semicircular in shape, multinucleated and highly polarized. They have an anterior, concave, innervated face, which exhibits positive histochemical reactions for acetylcholinesterase and for the nicotinic acetylcholine receptor. Multiple nerve-endings are covered with Schwann cell projections, similar to those present in skeletal muscle. Their posterior face is convex, non-innervated and is in contact with collagen fibres. 2. The cytoplasm of these electrocytes possesses abundant filamentous actin (F-actin), orderly distributed in the cell and exhibiting intense fluorescence with NBD-phallacidin. The F-actin is in contact with Z-lines as in muscle, and in contrast with Torpedo (Kordeli et al., 1986, 1987) and Discopyge (Vidal et al., 1986, 1989a) electrocytes, where it is confined to the non-innervated face. 3. Electrocytes of this Rajidae are an ideal model for the study of F-actin because of the similar embryological origin with skeletal muscle tissue and also because of the peculiar characteristics of their cytoplasm, packed full with F-actin. In addition, electric organs could constitute an alternative biological source for the study of the cholinergic synapse.
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PMID:Ultrastructure of Psammobatis extenta (Rajidae) electrolytes and cytochemical localization of acetylcholinesterase, acetylcholine receptor and F-actin. 755 May 72

A unique group of neurons in the submucous plexus of the gastrointestinal tract in guinea pigs was studied using (1) Nissl staining and an enzyme histochemical technique for acetylcholinesterase (AChE), (2) immunohistochemical methods for the localisation of neuron specific enolase (NSE) and neuropeptides, including vasoactive intestinal peptide (VIP), substance P (SP), somatostatin (SOM), calcitonin gene-related peptide (CGRP), leu-enkephalin (leu-ENK), neuropeptide (NPY) and cholecystokinin (CCK), (3) a fluorescence tracer technique involving the intraperitoneal (i.p.) injection of fluorogold, and (4) normal electron microscopy. The results showed that these neurons were distributed singly or in groups in the submucosa. They were closely adherent to the outer walls of lymphatic vessels, some appearing to protrude into the lumen. Ultrastructurally, only a thin layer of basal lamina and some collagen fibrils intervened between the endothelia of the lymphatic vessels and these neurons. Based on their synaptic contacts and the features of their content of synaptic vesicles, at least 4 types of axon terminal forming synaptic contacts with the 'lymphatic vessel-associated neurons' (LV-AN) were identified. The sources of origin of these terminals remains uncertain although it is speculated that they may be derived from vagal efferents or of intrinsic origin from the neighbouring neurons. All the LV-AN showed AChE and NSE positive reactions, but only a varying number were positive for VIP, SP, SOM, ENK, CGRP, CCK or NPY. The LV-AN were labelled with fluorogold injected i.p.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Studies of the lymphatic vessel-associated neurons in the intestine of the guinea pig. 755 16

We obtained a stable expression of acetylcholinesterase (AChE, E.C. 3.1.1.7) in the rat basoleukemia cell line, RBL-2H3, which possesses a well developed secretory pathway, but expresses only very little endogenous AChE. Metabolic labeling showed that AChEH and AChET, differing by C-terminal peptides encoded by alternatively spliced exons, were synthesized at a similar rate. When transfected with AChEH, RBL cells efficiently produced GPI-anchored dimers, which were mostly exposed at the cell surface, as shown both by activity and immunofluorescence labeling. In contrast, when transfected with AChET, RBL cells produced about tenfold less activity, which was essentially retained in the cell, and the enzyme could not be detected at the cell surface by immunolabeling. The fate of the enzyme is therefore determined by its C-terminal alternative peptides. We were also able to coexpress the AChET subunit with the collagenic Q subunit. The cells produced small but significant amounts of collagen-tailed forms, essentially A4. The expression of these different catalytic and structural subunits in stably transfected RBL cells will be useful to explore the regulated posttranslational processes involved in protein maturation and transport.
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PMID:Stable expression of acetylcholinesterase and associated collagenic subunits in transfected RBL cell lines: production of GPI-anchored dimers and collagen-tailed forms. 758 81

The collagen-tailed form of acetylcholinesterase (AChE) binds to heparin and heparan sulfate proteoglycans. We have employed synthetic peptides corresponding to the central collagenic region of the tail of AChE, to identify the heparin-binding domains of the tail of asymmetric AChE. Two putative heparin-binding consensus sequences were localized in the collagenic tail. Peptides containing such sequences (P-(145-159) and P-(249-262)) were able to release asymmetric AChE bound to heparin-agarose. A triple mutation, Asn-Asp-Gly-Gly instead of Arg-His-Gly-Arg, completely abolishes the capacity of the peptide P-(145-159) to elute AChE from the heparin column. Our results suggest that the interaction between the collagen-tailed AChE and proteoglycans is mediated by clusters of basic residues that form two belts around the triple helix of the collagenic tail.
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PMID:Two heparin-binding domains are present on the collagenic tail of asymmetric acetylcholinesterase. 774 33

Production of recombinant human acetylcholinesterase (AChE) by a high producer human embryonic kidney cell line (293) was evaluated by three main cell propagation systems; surface propagator, fixed-bed reactor and stirred microcarrier cultures. The recombinant cell line expresses AChE levels as high as 10-20 mg/l/day. System productivities in either the surface propagator (multitray system), or in the fixed-bed reactor (polyurethane macroporous sponges) were 4-8 mg AChE/l/day during a production period of 8 days. Similar productive rates, yet longer production periods (up to 22 days), were obtained in microcarrier (MC) cultures using either polystyrene beads (Biosilon); collagen-coated dextran beads (Cytodex-3); or gelatin macroporous beads (Cultispher-G). Best results were obtained in an aggregate culture using cellulose beads charged with diethylaminoethyl (DEAE) groups, (Servacel), as carriers. In this culture, a system productivity of 6-10 mg/l/day was maintained for 28 days.
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PMID:Evaluation of anchorage-dependent cell propagation systems for production of human acetylcholinesterase by recombinant 293 cells. 776 76

A congenital myasthenic condition has been described in several patients characterized by a deficiency in end-plate acetylcholinesterase (AChE). The characteristic form of AChE in the end-plate basal lamina has the catalytic subunits disulfide linked to a collagen-like tail unit. Southern analysis of the gene encoding the catalytic subunits revealed no differences between patient and control DNA. Genomic DNA clones covering exon 4 and the alternatively spliced exons 5 and 6 were analyzed by nuclease protection and sequencing. Although allelic differences were detected between controls, we found no differences in exonic and intronic areas that might yield distinctive splicing patterns in patients and controls. The ACHE gene was cloned from genomic libraries from a patient and a control. Transfection of the cloned genes revealed identical species of mRNA and expressed AChE. Cotransfection of the genes expressing the catalytic subunits with a cDNA from Torpedo encoding the tail unit yielded asymmetric species that require assembly of catalytic subunits and tail unit. thus the catalytic subunits of AChE expressed in the congenital myasthenic syndrome appear identical in sequence, arise from similar splicing patterns, and assemble normally with a tail unit to form a heteromeric species.
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PMID:Patients with congenital myasthenia associated with end-plate acetylcholinesterase deficiency show normal sequence, mRNA splicing, and assembly of catalytic subunits. 781 34


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