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)

In view of their supposed localization in extracellular structures, such as basal lamina, we have investigated the possible interactions of collagen-tailed forms of acetylcholinesterase from Electrophorus and bovine superior cervical ganglion with matrix proteins: laminin, fibronectin and types IV and V collagens. Using binding and sedimentation assays, with iodinated or non-radioactive matrix proteins, we have not observed any significant interaction, in conditions of high or low ionic strength. We also examined whether the collagen tail of acetylcholinesterase asymmetric forms possessed an immunological relationship with known collagen types (I, III, IV, V) from mammalian sources. We found no specific immunoreactivity with any of the 32 sera studied, either with the iodinated Electrophorus or with the native bovine enzyme. We conclude from these negative results that the collagen-like tail of acetylcholinesterase is clearly distinct from the classical types of collagen and that asymmetric forms of the enzyme do not interact specifically with the matrix proteins studied. This does not exclude the possibility of specific interactions with other components, remaining to be identified.
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PMID:Relationship of collagen-tailed acetylcholinesterase with basal lamina components. Absence of binding with laminin, fibronectin, and collagen types IV and V and lack of reactivity with different anti-collagen sera. 685 32

Previous studies have indicated that the asymmetric form of acetylcholinesterase is localized in the basement membrane zone of the neuromuscular junction. We find that the collagenous subunit of the enzyme is required for interactions with basement membrane components. Acetylcholinesterase (the A12 form) binds best to the basement membrane heparan sulfate proteoglycan and type V collagen, to a lesser extent to laminin, fibronectin, and type I collagen, but not to type IV collagen. In addition, the purified A12 enzyme as prepared from electric eel is associated with a heparan sulfate-like component which appears to be responsible for the aggregation of the enzyme at low ionic strength. We observed that the purified form of the enzyme reacted with antibodies to type V collagen, and to a lesser extent with anti-type I collagen antibody, but not with anti-type IV collagen antibody. These data suggest that the collagenous subunit of the enzyme may have some similarity to type V collagen and that the interaction of the collagenous subunit with a heparan sulfate proteoglycan may be involved in its binding to basement membrane in the neuromuscular junction.
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PMID:Interactions of asymmetric forms of acetylcholinesterase with basement membrane components. 686 10

We have distinguished three fractions of acetylcholinesterase (AcChoE; acetylcholine acetylhydrolase, EC 3.1.1.7) from Torpedo marmorata electric organs, according to their solubilization characteristics. The low-salt-aggregating collagen-tailed forms are soluble in high-salt buffers; their hydrodynamic properties ae not modified in the presence of detergents. They constitute the A fraction, which amounts to about a third of the tissue's AcChoE activity. The low-salt-soluble (LSS) and detergent-soluble (DS) fractions are not sensitive to ionic strength and collagenase. In the presence of nonionic detergents or bile salts, both fractions behave as a monodisperse "6.3S" form, the properties of which have been investigated mostly in the case of Triton X-100. Disulfide bond reduction dissociates the detergent form into a smaller "5S" form. These two forms are thought to be, respectively, detergent-associated dimers and monomers. In the absence of detergent, the LSS fraction is polydisperse: it contains a major 8S component, 11S and 14S components, and faster-sedimenting aggregates, which appear to represent dimers, tetramers, and higher polymers. The heterogeneity of the 8S component in gel filtration suggests that it also contains variable noncatalytic elements. Upon removal of the detergent the DS fraction forms ill-defined aggregates. Trypsin induces quaternary rearrangements of part of the 8S component into 11S and 14S components, which are still convertible into the detergent form; therefore trypsin probably digests noncatalytic elements. Pronase and proteinase K, on the other hand, convert the enzyme into a dimeric form, G2, that does not interact with detergents, probably by cleaving a minor fragment of the subunit that is involved in hydrophobic interactions.
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PMID:Collagen-tailed and hydrophobic components of acetylcholinesterase in Torpedo marmorata electric organ. 693 97

Five molecular forms of acetylcholinesterase can be solubilized from the peripheral and central nervous systems of the frog: they will be referred to as the 3.6, 6, 10.5, 14 and 18 S forms. They seem to be analogous to the forms present in endplate-rich and endplate-free regions of frog skeletal muscle. In particular the 18 and 14 S forms represent the collagen-tailed forms of frog acetylcholinesterase. These heavy forms are found in all peripheral and central tissues examined, including whole brain or regions of brain: cerebellum, telencephalon, optic tectum, spinal cord, spinal ventral and dorsal roots and sciatic nerve, as well as in glial or Schwann cellrich tissues devoid of neuronal elements, such as the filum terminale or the severed stump of the nerve, several weeks after section. The 18 S form may represent up to 30% of total acetylcholinesterase activity. It thus seems that the 14 S and 18 S forms are very widely distributed throughout most neuronal and non-neuronal tissues in amphibians.
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PMID:Ubiquitous presence of the tailed, asymmetric forms of acetylcholinesterase in the peripheral and central nervous systems of the frog (Rana temporaria). 697 36

The effects of collagen-like proteins on platelets were studied in human platelet-rich plasmas. The C1q subcomponent of complement (human), acetylcholinesterase (electric eel), and elastin (bovine) had no platelet aggregating activity, despite compositional homologies with collagen in terms of hydroxyproline, hydroxylysine, proline and glycine contents. Upon preincubation with platelets, acetylcholinesterase was incapable of preventing the platelet aggregation triggered by collagen, whereas elastin exerted a weak and inconsistent blocking action. In turn, native C1q strongly inhibited collagen-induced platelet aggregation and 'aggregated' C1q, obtained by ultracentrifugation of freeze-thawed monomeric C1q, had a potentiating effect. These findings confirm the highly specific character of the platelet action of C1q.
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PMID:Effect of collagen-like substances (C1q, acetylcholinesterase and elastin) on collagen-induced platelet aggregation. 698 97

Unlabeled collagenous proteins were quantified as inhibitors of binding of native, soluble, radioiodinated type I collagen to the fibroblast surface. Collagen types IV, V a minor cartilage isotype (1 alpha 2 alpha 3 alpha), and the collagenlike tail of acetylcholinesterase did not inhibit binding. Collagen types II and III behaved as competitive inhibitors of type I binding. Denaturation of native collagenous molecules exposed cryptic inhibitory determinants in the separated constituent alpha chains. Inhibition of binding by unlabeled type I collagen was not changed by enzymatic removal of the telopeptides. Inhibitory determinants were detected in cyanogen bromide-derived peptides from various regions of helical alpha 1 (I) and alpha 1(III) chains. The aminoterminal propeptide of chick pro alpha 1(I) was inhibitory for binding, whereas the carboxyterminal three-chain propeptide fragment of human type I procollagen was not. The data are discussed in terms of the proposal that binding to surface receptors initiates the assembly of periodic collagen fibrils in vivo.
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PMID:Binding of soluble type I collagen to fibroblasts: specificities for native collagen types, triple helical structure, telopeptides, propeptides, and cyanogen bromide-derived peptides. 715 46

The similarities between the tail of asymmetric acetylcholinesterase (AcChE) and collagen prompted us to investigate if asymmetric AcChE, like collagen, can interact with fibronectin. Gradient centrifugation studies revealed that asymmetric, but not globular, AcChE bound to fibronectin and could be cross-linked covalently to fibronectin by plasma transglutaminase. The interaction of asymmetric AcChE with fibronectin paralleled the interaction of fibronectin with collagen. These results raise the possibility that fibronectin may be involved in attaching asymmetric AcChE to cell surfaces.
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PMID:Cross-linking and binding of fibronectin with asymmetric acetylcholinesterase. 724 81

Rat obturator nerve 16S acetylcholinesterase (16S AChE) was separated by sucrose gradient velocity sedimentation and compared to the 16S form of AChE similarly derived from endplate regions of anterior gracilis muscles. The 16S AChE from both tissues could only be extracted in high ionic strength buffer; as it aggregated under low ionic strength conditions. Treatment of nerve and muscle 16S AChE with purified collagenase, in the presence of calcium, caused an identical "shift" in the enzyme's sedimentation coefficient to 17.5S. Other properties which were also equivalent for 16S AChE from both tissue sources included: an excess substrate inhibition above 2 x 10(-3) M acetylcholine and Km of 1.6 x 10(-4) M, relative sensitivity to the specific inhibitors BW284C51 (I50 of 5 x 10(-8) M) and Iso-OMPA (I50 of 5 x 10(-4) M), and a half maximal thermal inactivation at 62.5 degrees C. These and additional results indicate that the 16S forms of AChE in both tissues are analogous molecules, which have a highly asymmetric conformation probably containing a collagen-like domain. The present findings are also consistent with the view that motor neurons provide at least a fraction of the 16S AChE present at the neuromuscular junction.
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PMID:Properties of 16S acetylcholinesterase from rat motor nerve skeletal muscle. 732 60

The structure of the myenteric plexus in the lower esophageal, pyloric and ileo-caecal sphincters of cats is studied in semi-thin sections through impregnation and demonstration of cholinesterase. The plexus ganglia are shown to be well formed structures, with varied sizes and shapes, in the collagen between the muscle layers of the sphincters. Impregnation reveals clearly in them Dogiel's neurones of 1st and 2nd type. The neurones and the nerve bundles of the plexus manifest intensive cholinesterase activity. The morphological data obtained are discussed in view of some functional specificities of the sphincter regions.
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PMID:Structure of the myenteric plexus in the sphincters of cat gastro-intestinal tract. IV. Light-microscopic characteristics. 743 17

The ionic detergent sodium cholate, in the presence of 1 M NaCl, solubilizes a 20S acetylcholinesterase from chick retina and other brain tissues previously extracted with a buffered solution containing 1% Triton X-100 and 1 M NaCl. This 20S acetylcholinesterase appears to be a tailed form of the enzyme which, upon collagenase digestion, is converted to a 22S (mainly) form. This finding suggests that the vertebrate central nervous system does contain asymmetric, collagen-tailed forms of acetylcholinesterase, as is the case in skeletal muscle and cholinergic ganglia.
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PMID:Solubilization of 20S acetylcholinesterase from the chick central nervous system. 744 70


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