Molecular forms of acetylcholinesterase in the chick visual system

Villafruela, Maria J.; Barat, Ana; Villa, Salvador; Ramı́rez, Galo

doi:10.1016/0014-5793(80)80031-7

Cited by 24 publications

(12 citation statements)

References 27 publications

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“…They were, however, subsequently observed in the motor nerve itself [19,75,761, in various peripheral ganglia [23, 771 and, subsequently, in the central nervous system. Thus Ramirez and coworkers [78,79] clearly demonstrated the presence, in the chick visual system (i.e. in tectum and retina) of A forms displaying the same physicochemical parameters and collagenase sensitivity as the corresponding forms in chick skeletal muscle.…”

Section: Physicochemical Basis For Interaction With the Cell Surfacementioning

confidence: 92%

Modes of attachment of acetylcholinesterase to the surface membrane

Silman

Futerman

1987

European Journal of Biochemistry

173

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Acetylcholinesterase (AChE) occurs in multiple molecular forms differing in their quaternary structure and mode of anchoring to the surface membrane. Attachment is achieved by post‐translational modification of the catalytic subunits. Two such mechanisms are described. One involves attachment to catalytic subunit tetramers, via disulfide bridges, of a collagen‐like fibrous tail. This, in turn, interacts, primarily via ionic forces, with a heparin‐like proteoglycan in the extracellular matrix. A second such modification involve the covalent attachment of a single phosphatidylinositol molecule at the carboxyl‐terminus of each catalytic subunit polypeptide; the diacylglycerol moiety of the phospholipid serves to anchor the modified enzyme hydrophobically to the lipid bilayer of the plasma membrane. The detailed molecular structure of these two classes of acetylcholinesterase are discussed, as well as their biosynthesis and mode of anchoring.

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Section: Physicochemical Basis For Interaction With the Cell Surfacementioning

confidence: 92%

Modes of attachment of acetylcholinesterase to the surface membrane

Silman

Futerman

1987

European Journal of Biochemistry

173

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“…A general structural model of AChE has been defined on the basis of such evidence, which seems to fit equally well with the known properties of the enzyme from other verte brate sources, such as muscle and cholinergic ganglia [1,4,5,9,25,27,28,35,36]. It has be come customary in this kind of study to characterize and identify the different qua ternary structural forms of AChE in terms of their sedimentation properties, and we will follow this trend throughout this report to facilitate the interpretation and further dis cussion of our results.…”

Section: Introductionmentioning

confidence: 93%

“…Al though no such molecular species have yet been characterized in the central nervous sys tem [15,25,27,35] their existence is extremely likely, and we have described the presence in the chick visual system of collagen-tailed AChE molecular forms with sedimentation properties similar to the known synapse-spe cific forms [36], In the hope of finding a more extensive correlation between the molecular organization of the different forms of AChE, in the central nervous system, and their subcellular localization and/or potential function we have undertaken a systematic study of the different patterns of development of several molecular forms of AChE, characterized, as said, by definite sedimentation coefficients, in the chick retina and optic tectum. An exten sive number of developmental studies on AChE, both in chick and in other experi mental animals, have already appeared.…”

Section: Introductionmentioning

confidence: 99%

“…When measuring the specific activities of acetyl cholinesterase during development we used a radiometric procedure based on the release of [nC]-acetatc from [l-'*C]-acetylcholine, as previously described [23], In the case of gradient fractions we used Ellman's procedure (7] for peak localization, as described in a previous paper [36], and the above radiometric pro cedure for the subsequent quantitative analysis of the peaks. In all cases, 0.06 m M tetraisopropylpyrophosphoramide (Sigma) was used as a butyrylcholincsterase inhibitor.…”

Section: Enzymatic Assaysmentioning

confidence: 99%

“…When just the AChE-specific activity was being measured the tissue was homogeniz ed in 0.05 M potassium phosphate buffer, pH 6.8, containing 1 mM EDTA (K.*-) and 0.5% Triton X-100 [23!. Jn the sedimentation experiments, however, the retinas and optic lobes were homogenized in 10 vol of 10 mM Tris-HCI, pH 7,1 % Triton X-100,1 MNaCI, and 50 mM MgCI: (henceforth referred to as TrisTriton-sall buffer) [35,36]. The homogenization was performed in both cases at 4 °C in a glass-glass conical homogenizer (Kontes Duall).…”

Section: General Proceduresmentioning

confidence: 99%

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Molecular Forms of Acetylcholinesterase in the Developing Chick Visual System

et al. 1981

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The developmental profiles of the enzyme acetylcholinesterase, and of some of its quaternary structural forms, characterized by discrete sedimentation coefficients, have been comparatively analyzed in chick retina and optic tectum, between embryonic day 8 and day 10 after hatching. Four molecular species of AChE have been characterized in both retina and tectum during this developmental period: two of them with sedimentation coefficients of 11S and 6S, accounting together for 94–99% of the AChE activity in the initial homogenate, can be easily extracted by homogenization in a buffer containing 1 % Triton X-100 and 1 M NaCl, at 4°C. The other two, however, are not extractable by such treatment, but can be released by collagenase from the residue left after the detergent-salt extraction; they have apparent sedimentation coefficients of 21.5S and 16.5S and represent, together, less than 2% of the activity in the initial homogenate. All four forms of the enzyme show distinctive patterns of change during the developmental period considered, with significant differences between retina and tectum. These differences are discussed in the context of the specific roles of retina and tectum in the visual process.

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Compartmentalization of acetylcholinesterase in the chick retina

Ramı́rez¹,

Barat²,

Donoso³

et al. 1989

J of Neuroscience Research

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Using selective inhibitor treatments, we have studied the distribution of asymmetric (A) and globular (G) forms of acetylcholinesterase (AChE) in the extra- and intracellular compartments of chick retina, a specialized region of chick central nervous system (CNS). Our results show that the chick retinal collagen-tailed AChE (an example of class II asymmetric molecular forms) is essentially an extracellular form of the enzyme; this is the first demonstration of the extracellular localization of asymmetric AChE in the vertebrate CNS. The active site of most of the hydrophobic, membrane-bound G4-form is also exposed to the external environment. In turn, the smaller molecular weight G-forms (G2 and G1) are localized within the cells, where they may represent intermediate components in the assembly or degradation of the more complex enzymatic molecular species. Histoenzymatic ultrastructural techniques show internal AChE in amacrine as well as in ganglion cell bodies, and external enzyme, specifically associated with synapses and axons, in the inner plexiform layer. The probable cooperation of the extracellular A12-forms and the membrane-bound G species (mainly G4) of the enzyme to the hydrolysis of acetylcholine (ACh) released into the external compartment is suggested and discussed.

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Molecular forms of acetylcholinesterase in the chick visual system

Cited by 24 publications

References 27 publications

Modes of attachment of acetylcholinesterase to the surface membrane

Modes of attachment of acetylcholinesterase to the surface membrane

Molecular Forms of Acetylcholinesterase in the Developing Chick Visual System

Compartmentalization of acetylcholinesterase in the chick retina

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