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)

The appearance and distribution of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) in 12 human thyroid cancers and three normal thyroids were examined by electron microscopic study with indirect thiocholine method. The demonstration of AChE and BuChE activities in only two of nine cases of follicular and papillary carcinoma examined and none of the three cases of medullary carcinoma shows that the cholinesterases are not specific enzymes for the thyroid tumors. In normal thyroid tissue samples examined, no activities of AChE and BuChE were detected. On ultrastructural level AChE reaction product was revealed in the perinuclear space, in the endoplasmic reticulum, and in the Golgi complex of some but not in all cells in less-differentiated regions of the tumors. In contrast to the distribution of AChE, no staining for BuChE was noted in the Golgi elements. Ultrastructural localization of AChE activity in the thyroid cancer cells corresponds exactly to the current understanding of glycoproteins synthesis and processing in normal cells. The authors postulate that the copy of AChE gene suppressed in normal thyroid epithelium cells may be expressed in some follicular thyroid carcinoma cells. Their hypothesis is logical on the basis of recent finding of a significant homology between AChE and thyroglobulin.
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PMID:Acetylcholinesterase and butyrylcholinesterase activities in human thyroid cancer cells. 333 19

The 60-kDa esterase was isolated from liver microsomes of 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced rabbits and its complete amino acid sequence determined. Automated sequence analysis of intact protein, as well as characterization of the peptides obtained from enzymatic and chemical cleavages, led to the elucidation of the primary structure. The protein is a single polypeptide consisting of 539 residues and molecular weight 59,478. The active site serine is 195, and another diisopropylphospho binding site is at histidyl 441. Carbohydrate chains are attached at aspariginyl residues 61 and 363. Although 2,3,7,8-tetrachlorodibenzo-p-dioxin treatment induces this esterase severalfold, the amino acid sequence of the induced enzyme is identical to that of the enzyme isolated from liver microsomes of untreated rabbits. The sequence of the microsomal esterase is 30% identical with the sequences of human serum cholinesterase and the acetylcholinesterase from Torpedo californica. There is also a close homology between the 60-kDa esterase and the COOH-terminal domain of bovine thyroglobulin.
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PMID:Complete covalent structure of 60-kDa esterase isolated from 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced rabbit liver microsomes. 334 53

We have compared the amino acid sequences of proteins that are involved in acetylcholine (AcCho) metabolism and cholinergic neurotransmission: choline acetyltransferase (ChoAcTase), acetylcholinesterase (AcChoEase), and a neuronal alpha subunit of nicotinic AcCho receptor (AcChoR). A comparison of Drosophila ChoAcTase and rat neuronal alpha subunit of AcChoR shows a limited segmental type homology, which may suggest a similar acetylcholine binding site in the two proteins evolving by convergence. We note a global homology of 21-44% identity between Drosophila ChoAcTase and Torpedo AcChoEase. Six homologous segments of 40-60 amino acids cover 38% and 54% of the sequences, raising the possibility of a common evolutionary origin. We also note that mammalian thyroglobulin (TG), the precursor for thyroid hormones, contains an AcChoEase-like sequence at its carboxyl end. This homology raises the possibility that the gene for TG has evolved by gene fusion or condensation (i.e., recruiting a preexisting redundant copy of a gene for AcChoEase during vertebrate evolution). Our results demonstrate that the record of evolutionary history for nervous system proteins can be read across the boundaries of separation between vertebrates and invertebrates. They also provide molecular evidence for the common evolutionary origins of the nervous and endocrine systems in vertebrates--both evolving to make intercellular communication possible.
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PMID:Evolutionary origin of cholinergic macromolecules and thyroglobulin. 347 39

A cDNA encoding acetylcholinesterase (AChE) (EC 3.1.1.7) from Torpedo californica was isolated and from its nucleotide sequence the entire amino acid sequence of the processed protein and a portion of the leader peptide has been deduced. Approximately 70% of the tryptic peptides from the catalytic subunit of the 11 S form have been sequenced, and a comparison of the peptide sequences with the sequence inferred from the cDNA suggests that the cDNA sequence derives from mRNA for the 11 S form of the enzyme. The amino acid sequence is preceded by a hydrophobic leader peptide and contains an open reading frame encoding for 575 amino acids characteristic of a secreted globular protein. Eight cysteines, most of which are disulfide linked, are found along with four potential sites of N-linked glycosylation. The active-site serine is located at residue 200. Local homology is found with other serine hydrolases in the vicinity of the active site, but the enzyme shows striking global homology with the COOH-terminal portion of thyroglobulin. Further comparison of the amino acid sequences of the individual enzyme forms with other cDNA clones that have been isolated should resolve the molecular basis for polymorphism of the AChE species.
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PMID:Primary structure of acetylcholinesterase: implications for regulation and function. 353 98

The complete amino acid sequence of human serum cholinesterase (choline esterase II (unspecific), EC 3.1.1.8) was determined by Edman degradation of purified peptides. The protein contains 574 amino acids per subunit and nine carbohydrate chains attached to 9 asparagines. The four subunits of cholinesterase appear to be identical. The active site serine is the 198th residue from the amino terminus. The sequence of human serum cholinesterase is 53.8% identical with the sequence of acetylcholinesterase from Torpedo californica and 28% identical with the carboxyl-terminal portion of bovine thyroglobulin.
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PMID:Complete amino acid sequence of human serum cholinesterase. 354 89

The mRNA encoding human thyroglobulin has been cloned and sequenced. It is made up of a 8301-nucleotide segment encoding a preprotein monomer of 2767 amino acids, flanked by non-coding 5' and 3' regions of 41 and 106 nucleotides, respectively. This preprotein consists of a leader sequence of 19 amino acids, followed by the sequence of the mature monomer, corresponding to a polypeptide of 2748 amino acids (Mr = 302773). On its amino-terminal side, 70% of the monomer is characterized by the presence of three types of repetitive units. In contrast, the remaining 30% of the protein is devoid of repetitive units. This last region however shows an interesting homology (up to 64%) with the acetylcholinesterase of Torpedo californica. The sites of thyroid hormones synthesis are clustered at both ends of the thyroglobulin monomer. By contrast, the potential glycosylation sites are scattered along the polypeptide chain.
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PMID:Primary structure of human thyroglobulin deduced from the sequence of its 8448-base complementary DNA. 359 99

The homology between thyroglobulin and acetylcholinesterase (1) has been analyzed in detail. It contains 28.3% identical amino acids and extends over 544 residues, involving more than 90% of the acetylcholinesterase molecule and the C-terminal portion of thyroglobulin. The hydropathy profiles of the homologous regions have been determined and compared. Their striking resemblance suggests that both proteins adopt a similar three dimensional structure and militates for some common property. As thyroglobulin and acetylcholinesterase are known to interact with cell membranes, we suggest that the acetylcholinesterase-like domain of thyroglobulin is involved in the binding. These observations demonstrate that thyroglobulin has evolved from the condensation of a duplicated copy of the acetylcholinesterase gene with an archaic thyroglobulin gene encoding the major hormonogenic domain. The extensive homology in hydropathy profiles suggests that the two proteins may share antigenic determinants. If this were the case, it would provide a rationale for the demonstration of immunoreactive thyroglobulin in neurons (2) and the pathogenesis of Grave's ophthalmopathy.
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PMID:Analysis of sequence and structure homologies between thyroglobulin and acetylcholinesterase: possible functional and clinical significance. 371 7

Acetylcholinesterase, an essential enzyme of the nervous system, rapidly terminates the action of acetylcholine released into the synapse. Acetylcholinesterase is also found (in lower abundance) in extrajunctional areas of muscle and nerve and on erythrocyte membranes. Hydrodynamic analyses of the native enzyme and characterization of its dissociated subunits have revealed multiple enzyme forms which can be divided into two classes: dimensionally asymmetric forms which are usually found within the synapse and contain a collagen-like structural subunit disulphide-linked to the catalytic subunits; and globular forms which appear to be widely distributed on the outer surface of cell membranes. Both forms have been characterized in the ray Torpedo californica and, although their catalytic behaviours seem to be identical, they differ slightly in amino-acid composition, peptide maps and reactivity with certain monoclonal antibodies. Here, we report the complete amino-acid sequence of an acetylcholinesterase inferred from the sequence of a complementary DNA clone. The 575-residue protein shows significant homology with the C-terminal portion of thyroglobulin.
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PMID:Primary structure of Torpedo californica acetylcholinesterase deduced from its cDNA sequence. 375 47

The inter- and intrasubunit disulfide bridges for the 11 S form of acetylcholinesterase isolated from Torpedo californica have been identified. Localized within the basal lamina of the synapse, the dimensionally asymmetric forms of acetylcholinesterase contain either two (13 S) or three (17 S) sets of catalytic subunits linked to collagenous and noncollagenous structural subunits. Limited proteolysis of these molecules yields a tetramer of catalytic subunits that sediments at 11 S. Each catalytic subunit contains 8 cysteine residues which were identified following tryptic digestion of the reduced, 14C-carboxymethylated protein. The tryptic peptides were purified by gel filtration followed by reverse-phase high performance liquid chromatography (HPLC) and then sequenced. The disulfide bonding profile was determined by treating the native, nonreduced 11 S form of acetylcholinesterase with a fluorescent, sulfhydryl-specific reagent, monobromobimane, prior to tryptic digestion. Peptides again were resolved by gel filtration and reverse-phase HPLC. One fluorescent cysteine-containing peptide was identified, indicating that a single sulfhydryl residue, Cys231, was present in its reduced form. Three pairs of disulfide-bonded peptides were identified. These were localized in the polypeptide chain based on the cDNA-deduced sequence of the protein and were identified as Cys67-Cys94, Cys254-Cys265, and Cys402-Cys521. Hence, three loops are found in the secondary structure. Cys572, located in the carboxyl-terminal tryptic peptide, was disulfide-bonded to an identical peptide and most likely forms an intersubunit cross-link. Since the 6 cysteine residues in acetylcholinesterase that are involved in intrachain disulfide bonds are conserved in the sequence of the homologous protein thyroglobulin, it is likely that both proteins share a common folding pattern in their respective tertiary structures. Cys231 and the carboxyl-terminal cysteine residue Cys572 are not conserved in thyroglobulin.
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PMID:Profile of the disulfide bonds in acetylcholinesterase. 375 80

In the present study we analysed by ELISA the ability of sera from 50 patients with myasthenia gravis (MG), 20 with Hashimoto's thyroiditis (HT), 53 with Graves' disease (GD) and 36 healthy controls (CR) to react with acetylcholinesterase (AChE) from Electrophorus electricus and human thyroglobulin (Tg). Significantly increased anti-AChE activity was exhibited by a high proportion of MG (IgG 36%) and GD (IgG 21%) sera, while increased anti-Tg activity was detected in all three patient groups (MG, IgG 26% and IgA 26%; HT, IgG 85% and IgA 40%; and GD, IgG 51%). Interestingly, a significant proportion of MG and GD sera exhibited both IgG anti-AChE and anti-Tg activities (MG, 18%; P < 0.001; and GD, 15%; P < 0.001, versus CR, 0%). This bi-reactivity was exhibited by anti-AChE antibodies cross-reacting with Tg (anti-AChE/Tg activity); (i) serum anti-AChE activity was effectively inhibited by soluble Tg, and (ii) affinity-purified anti-Tg antibodies cross-reacted with AChE. Cross-reactivity seems to be a property of pathological (auto)antibodies; induced (rabbit) antibodies to AChE or Tg were highly monospecific. Analysis of clinical data showed that increased IgG anti-AChE/Tg activity was well associated with: (i) overlapping GD in MG (P < 0.02), and (ii) ophthalmopathy in GD (P < 0.01). In contrast, no correlation was noted in MG between anti-AChE activity units and anti-Tg activity units or acetylcholine receptor antibody titres. The clinical significance of anti-AChE/Tg antibodies remains to be elucidated.
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PMID:Antibodies to acetylcholinesterase cross-reacting with thyroglobulin in myasthenia gravis and Graves's disease. 774 74


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