Effects of Acute and Chronic Denervation on Release of Acetylcholinesterase and Its Molecular Forms in Rat Diaphragms

Carter, Jonathan L.; Brimijoin, Stephen

doi:10.1111/j.1471-4159.1981.tb01695.x

Cited by 45 publications

(13 citation statements)

References 25 publications

(19 reference statements)

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“…The A1Z form, which is specifically found at the neuromuscular junction in the rat (Fernandez et al, 1979;Vigny et al, 1976), is considered to be a sensitive marker of alterations in the relationship between muscle and nerve (Carter and Brimijoin, 1981;Vigny et al, 1976). In our study, however, the A12 form was the least sensitive.…”

Section: Discussioncontrasting

confidence: 65%

Neurobiology of Acetylcholine

Dun¹,

Perlman²,

Karczmar³

1987

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Section: Discussioncontrasting

confidence: 65%

Neurobiology of Acetylcholine

Dun¹,

Perlman²,

Karczmar³

1987

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“…We conclude that the 20-kDa hydrophobic anchors of brain AChE does not include a peptide encoded by E PRAD and therefore does not derive from the COLQ gene. Although the Q R transcript is not responsible for AChE anchoring in the membrane, it might play a role in the production of soluble tetrameric molecules (G 4 na ), which are secreted at the neuromuscular junction (34) and may somehow become attached to the synaptic basal lamina (35). In skeletal muscle, heart, and brain, the exon E PRAD was found to be associated to collagen exons, in rQ1 or to readthrough sequence, in rQ R .…”

Section: A Single Gene Encodes the Collagen Tail Of Ache And Bchementioning

confidence: 99%

The Mammalian Gene of Acetylcholinesterase-associated Collagen

Krejci¹,

Thomine²,

Boschetti³

et al. 1997

Journal of Biological Chemistry

167

144

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The collagen-tailed or asymmetric forms (A) represent a major component of acetylcholinesterase (AChE) in the neuromuscular junction of higher vertebrates. They are hetero-oligomeric molecules, in which tetramers of catalytic subunits of type T (AChE T ) are attached to the subunits of a triple-stranded collagen "tail." We report the cloning of a rat AChE-associated collagen subunit, Q. We show that collagen tails are encoded by a single gene, COLQ. The ColQ subunits form homotrimers and readily form collagen-tailed AChE, when coexpressed with rat AChE T . We found that the same ColQ subunits are incorporated, in vivo, in asymmetric forms of both AChE and butyrylcholinesterase. A splice variant from the COLQ gene encodes a proline-rich AChE attachment domain without the collagen domain but does not represent the membrane anchor of the brain tetramer. The COLQ gene is expressed in cholinergic tissues, brain, muscle, and heart, and also in noncholinergic tissues such as lung and testis.Acetylcholinesterase (AChE, EC 3.1.1.7)1 is highly concentrated at vertebrate neuromuscular junctions. This enzyme is encoded by a single gene, and adult mammalian muscles express a single splice variant, corresponding to the catalytic subunit of type T (AChE T ) (1, 2). At the post-translational level, however, quaternary interactions introduce a considerable diversity of molecular forms that are characterized by distinct localizations in cellular structures. These molecules include amphiphilic monomers (G 1 a ) and dimers (G 2 a ), nonamphiphilic tetramers (G 4 na ), as well as hetero-oligomeric structures in which tetramers of catalytic subunits are disulfide-linked with a hydrophobic "tail" (20 kDa) in the membrane-bound G 4 a forms (3, 4) or with a collagenous "tail" in the collagen-tailed or asymmetric (A) forms. The latter molecules consist of one, two, or three tetramers (A 4 , A 8 , A 12 ), which are disulfide-linked to the strands of the triple helical collagen tail (see Fig. 1A). G 1 a and G 2 a forms appear to remain mostly intracellular and represent precursors of more complex molecules. The G 4 na form is secreted and hydrophobic-tailed tetramers (G 4 a ) are attached to the plasma membrane. The collagen-tailed molecules are tethered in the basal lamina, and are largely responsible for the high concentration of AChE at the neuromuscular junction.To understand the biosynthesis of the various AChE forms and its regulation, it is necessary to analyze the association of AChE T catalytic subunits with anchoring subunits, particularly the collagen subunits, which have been named Q, according to the nomenclature of AChE-associated proteins (5). Cloning and expression of the collagen tail subunit of the asymmetric AChE forms from Torpedo electric organ (tQ 1 ) allowed us to show that the structural and catalytic subunits assemble into collagen-tailed molecules when coexpressed in COS cells (6). The primary sequence of the Q subunit comprises an N-terminal region, Q N , a collagen domain, and a C-terminal domain, Q C . We showe...

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“…This figure was reached by comparing the total AChE activity of rat hindlimb musculature with the total supply of enzyme activity by axonal transport along the sciatic nerve. In contrast, we have recently shown that the release of AChE activity from rat diaphragm in vitro would alone deplete this muscle of AChE in only 8 days (Carter and Brimijoin, 1981).…”

mentioning

confidence: 76%

“…Homogenates were centrifuged at 10,000 x g for 10 min at 4" and duplicate 50-pl portions of the supernatant fractions were assayed for AChE activity by the radiometric method of Potter (1967). As previously described (Carter and Brimijoin, 1981), the substrate consisted of 25 nCi of [ "Clacetate-labeled acetylcholine (New England Nuclear Corp., Boston) with unlabeled acetylcholine chloride added to reach a final concentration of 1 mM (several times the K,, but below the level at which substrate inhibition occurs). Ethopropazine (lo-4 M) was added to all reaction mixtures to inhibit butyrylcholinesterase by more than 99%.…”

mentioning

confidence: 99%

Turnover of the Molecular Forms of Acetylcholinesterase in the Rat Diaphragm

Brimijoin¹,

Carter²

1982

Journal of Neurochemistry

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The turnover of acetylcholinesterase (AChE) and its molecular forms was measured by following the loss of enzyme activity in the right hemidiaphragms of Sprague-Dawley rats treated with cycloheximide, 20 mg/kg, every 4 h. This treatment inhibited 96% of the incorporation of [3H]leucine into muscle protein. After 8 h of treatment, the total AChE activity of the diaphragm decreased by 17% (P less than 0.01). Assuming first-order exponential kinetics, a half-life of 30 h and an hourly turnover of 180 units were calculated. The measured accumulation of AChE activity at a ligature on the phrenic nerve indicated that axonal transport contributed trivially to this turnover. Sucrose density gradient experiments showed that the cycloheximide-induced low of AChE activity was restricted to the 4S enzyme, which had an apparent half-life of 6.2 h.

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Effects of Acute and Chronic Denervation on Release of Acetylcholinesterase and Its Molecular Forms in Rat Diaphragms

Cited by 45 publications

References 25 publications

Neurobiology of Acetylcholine

Neurobiology of Acetylcholine

The Mammalian Gene of Acetylcholinesterase-associated Collagen

Turnover of the Molecular Forms of Acetylcholinesterase in the Rat Diaphragm

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