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)

Quantitative solubilization of the phospholipid-associated form of acetylcholinesterase (AChE) from Torpedo electric organ can be achieved in the absence of detergent by treatment with phosphatidylinositol-specific phospholipase C (PIPLC) from Staphylococcus aureus [Futerman, Low & Silman (1983) Neurosci. Lett. 40, 85-89]. The sedimentation coefficient on sucrose gradients of AChE solubilized in detergents (DSAChE) varies with the detergent employed. However, the coefficient of AChE directly solubilized by PIPLC is not changed by detergents. Furthermore, PIPLC can abolish the detergent-sensitivity of the sedimentation coefficient of DSAChE purified by affinity chromatography, suggesting that one or more molecules of phosphatidylinositol (PI) are co-solubilized with DSAChE and remain attached throughout purification. DSAChE binds to phospholipid liposomes, whereas PIPLC-solubilized AChE and DSAChE treated with PIPLC do not bind even to liposomes containing PI. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis shows that PIPLC-solubilized AChE, like unmodified DSAChE, is a catalytic subunit dimer; electrophoresis in the presence of reducing agent reveals no detectable difference in the Mr of the catalytic subunit of unmodified DSAChE, of AChE solubilized by PIPLC and of AChE solubilized by Proteinase K. The results presented suggest that DSAChE is anchored to the plasma membrane by one or more PI molecules which are tightly attached to a short amino acid sequence at one end of the catalytic subunit polypeptide.
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PMID:Physicochemical behaviour and structural characteristics of membrane-bound acetylcholinesterase from Torpedo electric organ. Effect of phosphatidylinositol-specific phospholipase C. 298 94

A major glycoprotein of rat hepatoma plasma membranes was selectively released as a soluble form by incubating the membrane with phosphatidylinositol-specific phospholipase C. The soluble form corresponding to the glycoprotein was also prepared by butan-1-ol extraction of microsomal membranes at pH 5.5, whereas extraction at pH 8.5 yielded an electrophoretically different form with a hydrophobic nature. The soluble glycoprotein extracted at pH 5.5 was purified by sequential chromatography on concanavalin A-Sepharose, Sephacryl S-300 and anti-(alkaline phosphatase) IgG-Sepharose, the last step being used to remove a contaminating alkaline phosphatase. The glycoprotein thus purified was a single protein with Mr 130,000 in SDS/polyacrylamide-gel electrophoresis, although it behaved as a dimer in gel filtration on Sephacryl S-300. The glycoprotein was analysed for amino acid and carbohydrate composition. The composition of the carbohydrate moiety, which amounted to 64% by weight, suggested that the glycoprotein contained much larger numbers of N-linked oligosaccharide chains than those with O-linkage. It was confirmed that the purified glycoprotein was immunologically identical not only with that released by the phospholipase C but also with the hydrophobic form extracted with butan-1-ol at pH 8.5. The results indicate that the glycoprotein of rat hepatoma plasma membranes, which has an unusually high content of carbohydrate, is another membrane protein released by phosphatidylinositol-specific phospholipase C, as documented for alkaline phosphatase, acetylcholinesterase and Thy-1 antigen.
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PMID:Purification and characterization of a major glycoprotein in rat hepatoma plasma membranes. One of the membrane proteins released by phosphatidylinositol-specific phospholipase C. 303 62

The ability of phosphatidylinositol-specific phospholipase C (PIPLC) to solubilize acetylcholinesterase (AChE) in the electromotor system of adult Torpedo ocellata and in the developing electric organ was examined. PIPLC solubilizes significant amounts of the membrane-bound G2 form of AChE throughout embryonic development of the electric organ, as it does in the adult electric organ, the AChE of which we have shown to contain covalently bound inositol in its membrane-anchoring domain. In the electromotor system of the mature fish, PIPLC solubilizes almost quantitatively the AChE dimer in the electromotor axon as in the electric organ itself, but the corresponding fraction in the electric lobe is almost totally resistant to the phospholipase. This finding implies that the covalently bound phosphatidylinositol is added concomitantly with axonal transport. A substantial part of the G2 form in back muscle is sensitive to PIPLC, whereas the G4 tetramer of Torpedo brain is completely resistant.
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PMID:Differential susceptibility to phosphatidylinositol-specific phospholipase C of acetylcholinesterase in excitable tissues of embryonic and adult Torpedo ocellata. 304 Jan 64

Two enzymes, alkaline phosphatase and acetylcholinesterase (AChE), have been shown previously to be components of the surface of the trematode parasite Schistosoma mansoni. In this study we report that both these enzymes and other serine hydrolases are susceptible to release from the S. mansoni tegumental membrane by a phosphatidylinositol-specific phospholipase C (PIPLC) of bacterial origin. These data suggest that AChE and alkaline phosphatase of S. mansoni, as in higher organisms, are anchored to the membrane via covalently attached phosphatidylinositol. The release of AChE from the vesicular fraction of the parasite with PIPLC occurs in a concentration-dependent manner. Sucrose gradient centrifugation of the PIPLC-released AChE showed a single 8.3 S molecular form, similar to that observed for AChE solubilized by Triton X-100. PIPLC removed large amounts of AChE from the surface of intact schistosomula in culture, with no impairment of the viability of the parasite. In this case, an increase in the overall levels of AChE in the intact parasite was observed after addition of PIPLC.
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PMID:Acetylcholinesterase in Schistosoma mansoni is anchored to the membrane via covalently attached phosphatidylinositol. 313 66

We have isolated a COOH-terminal tryptic peptide from the hydrophobic globular (5.6 S) form of Torpedo californica acetylcholinesterase that exhibits divergence in amino acid sequence from the catalytic subunit of the dimensionally asymmetric (17 S + 13 S) enzyme. The divergent peptide could be recovered from the glycophospholipid-modified 5.6 S enzyme only after treatment with phosphatidylinositol-specific phospholipase C. Upon reduction, carboxymethylation with [14C]iodoacetate, and trypsin digestion the resultant peptides were purified by gel filtration followed by high performance liquid chromatography. The high performance liquid chromatography profiles of 14C-labeled cysteine peptides from lipase-treated 5.6 S enzyme revealed unique radioactive peaks which had not been present in digests of the asymmetric form. These peaks all yielded identical amino acid sequences. The difference in chromatographic behavior of the individual peptides most likely reflects heterogeneity in post-translational processing. Gas-phase sequencing and composition analysis are consistent with the sequence: Leu-Leu-Asn-Ala-Thr-Ala-Cys. Composition includes 2-3 mol each of glucosamine and ethanolamine which is indicative of modification by glycophospholipid. Glucosamine is also present in an asparagine-linked oligosaccharide. The two forms of acetylcholinesterase diverge after the threonine residue within this peptide sequence; the hydrophobic form terminates with cysteine whereas the asymmetric form extends for 40 residues beyond the divergence. The locus of divergence and absence of any other amino acid sequence difference suggest that the molecular forms of acetylcholinesterase arise from a single gene by alternative mRNA processing.
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PMID:Divergence in primary structure between the molecular forms of acetylcholinesterase. 333 34

Bovine erythrocyte acetylcholinesterase, a glycosylinositol phospholipid anchored membrane enzyme, was digested with phosphatidylinositol-specific phospholipase C and the released glycerol-containing moieties were identified and quantitated. About 96% of the total was alkylacylglycerol, of which sn-1-stearyl-2-stearoylglycerol, sn-1-stearyl-2-oleoylglycerol and sn-1-oleyl-2-stearoylglycerol accounted for 69%, 13% and 10%, respectively. These alkylacylglycerols are in marked contrast to the exclusively diacylglycerol species present in phosphatidylinositol from bovine erythrocyte membranes. This difference suggests that assembly of the membrane anchor of Ebo AChE involves a selected cellular pool of diradylglycerols.
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PMID:Alkylacylglycerol molecular species in the glycosylinositol phospholipid membrane anchor of bovine erythrocyte acetylcholinesterase. 333 15

The susceptibility to phosphatidylinositol-specific phospholipase C of the membrane associated acetylcholinesterase (AChE) forms of Xenopus laevis skeletal muscle was examined. This treatment released almost all the detergent-soluble AChE species from muscle homogenates. Sucrose gradient analysis showed that the released acetylcholinesterase form corresponds to a hydrophilic G2 dimer, indicating that this dimer has a glycolipid anchoring domain which contains phosphatidylinositol.
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PMID:A membrane-associated dimer of acetylcholinesterase from Xenopus skeletal muscle is solubilized by phosphatidylinositol-specific phospholipase C. 341 41

The temperature-dependence of the catalytic activity of acetylcholinesterase (AChE) from rat erythrocyte-ghost membranes and from Torpedo electric-organ membranes was examined. In the case of rat erythrocyte AChE, a non-linear Arrhenius plot was observed both before and after solubilization by a phosphatidylinositol-specific phospholipase C or by proteinase treatment. Similarly, no significant differences were observed in Arrhenius plots of Torpedo electric-organ AChE before or after solubilization. These results support our suggestion that the catalytic subunit of AChE does not penetrate deeply into the lipid bilayer of the plasma membrane and also suggest that care must be taken in ascribing break points in Arrhenius plots of membrane-bound enzymes to changes in their lipid environment.
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PMID:Arrhenius plots of acetylcholinesterase activity in mammalian erythrocytes and in Torpedo electric organ. Effect of solubilization by proteinases and by a phosphatidylinositol-specific phospholipase C. 390 34

The hydrophobic, membrane-bound form of Torpedo acetylcholinesterase is specifically solubilized by a phosphatidylinositol-specific phospholipase C, suggesting that acetylcholinesterase is bound to the membrane via a direct and specific interaction with phosphatidylinositol (Futerman et al., Biochem. J. (1985) 226, 369-377). Here we demonstrate the presence of covalently bound inositol in the membrane-anchoring domain of purified Torpedo acetylcholinesterase. Upon removal of this domain, levels of inositol are reduced to only 15-20% of those found in the intact enzyme. The results presented strongly support our suggestion that phosphatidylinositol is indeed involved in anchoring acetylcholinesterase to the plasma membrane.
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PMID:Identification of covalently bound inositol in the hydrophobic membrane-anchoring domain of Torpedo acetylcholinesterase. 400 81

Bovine erythrocytes were treated with each of three bacterial phospholipases C; phosphatidylcholine-hydrolyzing phospholipase C (PCase) of Clostridium perfringens, sphingomyelinase C (SMase) of Bacillus cereus and phosphatidylinositol-specific phospholipase C (PIase) of Bacillus thuringiensis. An increase in osmotic fragility was detected by means of a coil planet centrifugation (CPC) apparatus (Biomedical Systems Co., Tokyo) after the treatment with these enzymes. The peak of hemolysis normally observed in the untreated erythrocytes at the range between 50 and 100 mOsM shifted to 160 to 200 mOsM with the progress of sphingomyelin hydrolysis by phospholipase C of C. perfringens. Sphingomyelinase C of B. cereus showed two different effects on bovine erythrocytes: In the absence of divalent cations or in the presence of Ca2+ alone, the peak of hemolysis shifted to the region from 130 to 160 mOsM, without appreciable hydrolysis of sphingomyelin, while in the presence of Mg2+ or Mg2+ plus Ca2+, the peak of hemolysis further shifted to the region from 160 to 200 mOsM with the hydrolysis of sphingomyelin. Abrupt shift in osmotic fragility to a much higher region around 250 mOsM was produced by treatment with increasing amounts of phosphatidylinositol-specific phospholipase C. In this case, a significant amount of acetylcholinesterase was released from the erythrocyte membrane without hot or hot-cold hemolysis. The mechanism of alteration of osmotic fragility of bovine erythrocytes by treatment with phospholipases C seems to differ from case to case, depending upon the specific action of each enzyme toward the membrane phospholipids.
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PMID:Increase in osmotic fragility of bovine erythrocytes induced by bacterial phospholipases C. 630 97


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