16 S acetylcholinesterase in endplate-free regions of developing rat diaphragm

Sketelj, Janez; Brzin, Miro

doi:10.1007/bf00964786

Cited by 52 publications

(23 citation statements)

References 21 publications

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“…In the rat, 26 to 40% of the AChE activity is associated specifically with endplates; the balance is distributed throughout the muscle as nonendplate enzyme (Hall, 1973;Vigny et al, 1976;Younkin et al, 1982). The nonendplate enzyme in rat skeletal muscle is composed almost entirely of globular 10 S (G4) and 4 S (G1) forms (Hall, 1973;Vigny et al, 1976;Bon et al 1979;Younkin et al, 1982), although asymmetric forms clearly comprise a small component of the nonendplate AChE in the rat diaphragm (Sketelj and Brzin, 1980;Younkin et al, 1982). The asymmetric forms of AChE are of particular interest because they are highly concentrated in the endplate region of adult rat skeletal muscle (Hall, 1973;Vigny et al, 1976;Younkin et al, 1982) and appear to comprise virtually all (at least 84%) of the external AChE that is associated specifically with endplates (Yom&in et al, 1982).…”

Section: Discussionmentioning

confidence: 99%

Cellular localization of the molecular forms of acetylcholinesterase in cultured embryonic rat myotubes

1982

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Three different methods were used to quantitate the external and intracellular acetylcholinesterase (AChE) in cultured embryonic rat myotubes. The results from these methods were in excellent agreement and showed that one-fourth of the AChE is external and three-fourths is intracellular in these cells. The molecular forms of AChE in the intracellular and external compartments then were analyzed. To isolate intracellular AChE, external AChE was inactivated irreversibly by treating myotubes at 2°C with 10 PM methanesulfonyl fluoride and 100 PM decamethonium for 1 hr. To isolate external AChE, myotubes at 2°C were first exposed to 1.0 PM echothiophate for 15 min to protect (diethylphosphorylate) external AChE and then treated with 1.0 mM methanesulfonyl fluoride for 30 min at 37°C to inactivate intracellular AChE irreversibly. Control myotubes and myotubes in which the external or intracellular enzyme had been isolated were extracted sequentially to separate globular, asymmetric, and nonextractable AChE. Individual globular and asymmetric forms then were analyzed by velocity sedimentation on sucrose gradients. The fractions in which external enzyme had been isolated as diethylphosphorylated AChE were reactivated with l-methyl-2-hydroxyiminomethylpyridinium prior to analysis. Our data indicate that intracellular and external AChE have different compositions. Intracellular AChE is 79% globular forms (20% 10 S and 59% 4 S), 17% asymmetric forms (6% 16 S, 5% 12.5 S, and 7% other), and 4% nonextractable enzyme. External AChE is 55% globular forms (26% 10 S and 29% 4 S), 32% asymmetric forms (12% 16 S, 10% 12.5 S, and 10% other), and 13% nonextractable enzyme; therefore external enzyme is composed of relatively more 10 S, 16 S, 12.5 S, and nonextractable AChE and relatively less 4 S AChE. The most striking finding to emerge from this study is that the globular and asymmetric forms are all predominantly intracellular in cultured embryonic rat myotubes. Our results indicate that 85% of the 4 S, 69% of the 10 S, 59% of the 16 S, and 56% of the 12.5 S forms are intracellular. These results support the hypothesis that the 10 S and asymmetric forms of AChE are assembled intracellularly from 4 S precursors.The enzyme acetylcholinesterase (AChE) occurs in a isolated from the electric organ of the eel Electrophorus number of molecular forms. Three of these forms are electricus. The three asymmetric forms are designated globular proteins and three are asymmetric. The globular Ad, As, and Alz and consist of one, two, forms are monomers, dimers, and tetramers of the basic or three tetrameric assemblies of identical catalytic subcatalytic subunit designated G1, Gz, and Gd (Bon et al., units attached to an elongated collagen-like tail Vigny et al., 1979). The structure of the asymmetric al. Rosenberry and Richardson, 1977; Anglister forms has been analyzed most carefully using AChE and Silman, 1978).

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Section: Discussionmentioning

confidence: 99%

Cellular localization of the molecular forms of acetylcholinesterase in cultured embryonic rat myotubes

1982

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“…In rat and mouse, numerous studies have shown that the expression and distribution of AChE forms in muscles depend on age, on the fast or slow type of muscle, and on activity (Sketelj and Brzin, 1980;Lømo et al, 1985;Toutant and Massoulié, 1988). During development, AChE T transcripts in muscle fibers accumulate beneath the synaptic contacts as soon as they are established (Legay et al, 1995).…”

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Differences in Expression of Acetylcholinesterase and Collagen Q Control the Distribution and Oligomerization of the Collagen-Tailed Forms in Fast and Slow Muscles

et al. 1999

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The collagen-tailed forms of acetylcholinesterase (AChE) are accumulated at mammalian neuromuscular junctions. The A 4 , A 8 , and A 12 forms are expressed differently in the rat fast and slow muscles; the sternomastoid muscle contains essentially the A 12 form at end plates, whereas the soleus muscle also contains extrajunctional A 4 and A 8 forms. We show that collagen Q (ColQ) transcripts become exclusively junctional in the adult sternomastoid but remain uniformly expressed in the soleus. By coinjecting Xenopus oocytes with AChE T and ColQ mRNAs, we reproduced the muscle patterns of collagen-tailed forms. The soleus contains transcripts ColQ1 and ColQ1a, whereas the sternomastoid only contains ColQ1a. Collagentailed AChE represents the first evidence that synaptic components involved in cholinergic transmission may be differently regulated in fast and slow muscles.

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“…When rat muscle, for example, is chronically denervated in vivo, AChE decreases both in total content and in the form (16 S) suggested to be endplate-specific (Hall, 1973 ;Vigny, Koenig and Rieger, 1976 ;Sketelj and Brzin, 1980 .…”

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confidence: 99%

“…However, such analysis after gross excision of endplate-rich zones does not exclude the possibility that some other forms are present, both inside and outside the endplate. Further, the specific association of H 2c with the endplates has been questioned after similar experiments on human (Carson et al, 1979) and immature rat (Sketelj and Brzin, 1980) fig. 1 C, which shows that both the amount of AChE and the pattern of its forms is the same in dystrophic and normal birds.…”

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confidence: 99%

Molecular forms of acetylcholinesterase and pseudocholinesterase in chicken skeletal muscles : their distribution and change with muscular dystrophy

Barnard¹,

Lyles²,

Silman³

et al. 1982

Reprod. Nutr. Dévelop.

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16 S acetylcholinesterase in endplate-free regions of developing rat diaphragm

Cited by 52 publications

References 21 publications

Cellular localization of the molecular forms of acetylcholinesterase in cultured embryonic rat myotubes

Cellular localization of the molecular forms of acetylcholinesterase in cultured embryonic rat myotubes

Differences in Expression of Acetylcholinesterase and Collagen Q Control the Distribution and Oligomerization of the Collagen-Tailed Forms in Fast and Slow Muscles

Molecular forms of acetylcholinesterase and pseudocholinesterase in chicken skeletal muscles : their distribution and change with muscular dystrophy

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