Membrane vesicle structure

Even though dynein, kinesin, and myosin serve similar ATPase-dependent chemomechanical functions and have structural similarities, they do not appear to be related to each other in molecular terms. Their similarity lies in the overall shape of the molecule, which is composed of a pair of globular heads that bind microtubules and a fan-shaped tail piece (not present in myosin) that is suspected to carry the attachment site for membranous vesicles and other cytoplasmic components transported by MT. The cytoplasmic and axonemal dyneins are similar in structure (Hirokawa et al., 1989 Holzbaur and Vallee, 1994). Current studies on mutant phenotypes are likely to lead to a better understanding of the cellular roles of molecular motor proteins and their mechanisms of action (Endow and Titus, 1992). 

Histopathological features are dominated by the large number of centrally-placed muscle nuclei, sometimes affecting more than 90% of muscle fibers. The nuclei form long chains in the middle of the fiber and are surrounded by cytoplasm, which contains mitochondria and membranous vesicles, but no myofibrils. This morphological appearance has prompted comparison with myotubes, and in fact centronuclear myopathies are sometimes referred to as myotubular myopathies. This is a misnomer, however, since although the affected fibers retain some of the structural features of myotubes, and maturational arrest may play a role in their formation, the vast majority of such fibers are fully differentiated histochemically into either type 1 or type 2. 

Beveridge TJ (1999) Structures of Gram-negative cell walls and their derived membrane vesicles. J Bacteriol 181 4725 1733... 

Pesacreta TC, Lucas WJ. Plasma membrane coat and a coated vesicle-associated reticulum of membranes Their structure and possible interrelationship in Chara corallina. J Cell Biol 1984 98 1537-1545. 

One approach could be the attempt to include the lipids into the stabilization process. Lipid molecules bearing polymerizable groups can actually be arranged as planar monolayers or as spherical vesicles and polymerized by high energy irradiation within these membrane like structures under retention of the orientation of the molecules (8,9,36). 

Kobayashi, M., Suruga, S., Takeuchi, H., Sugawara, M., Iseki, K., and Miyazaki, K. A structure-relationship study of the uptake of aliphatic polyamine compounds by rat intestinal brush-border membrane vesicles, / Pharm. Pharmacol., 49(5) 511-515, 1997. 

This broad class of hydrolases constitutes a special category of enzymes which bind to and conduct their catalytic functions at the interface between the aqueous solution and the surface of membranes, vesicles, or emulsions. In order to explain the kinetics of lipolysis, one must determine the rates and affinities that govern enzyme adsorption to the interface of insoluble lipid structures -. One must also account for the special properties of the lipid surface as well as for the ability of enzymes to scooC along the lipid surface. See specific enzyme Micelle Interfacial Catalysis... 

S.4.3.2 Liquid Crystals The important enhancement of the hydrophobic character, due to the presence of fluoroalkyl tails, favors the auto assembly of amphiphilic fluorinated compounds when they are dispersed in water or in other solvents. They allow the formation of organized structures such a as fdms, membranes, vesicles, and tubules. 

Franke, W. W. and Keenan, T. W. 1979. Interaction of secretory vesicle membrane coat structures with membrane free areas of forming milk lipid globules. J. Dairy Sci. 62, 1322-1325. 

Molecular organization and self-assembly into layers, membranes, vesicles etc., construction of multilayer films [7.1-7.5], generation of defined aggregate morphologies [4.74, 4.75, 7.6-7.8J etc., make it possible to build up specific supramolecular architectures. The polymerization of the molecular components has been a major step in increasing control over the structural properties of such assemblies [7.9-7.13]. 

Both endocytosis of material at the plasma membrane and exocytosis from the Golgi apparatus involve the formation of clathrin-coated pits and vesicles. On the cytosolic side of the membrane these structures have an electron-dense coat consisting mainly of the protein clathrin, the polypeptides of which form a three-legged structure known as a triskelion. The clathrin triskelions assemble into a basket-like convex framework that causes the membrane to invaginate at that point and eventually to pinch off and form a vesicle. In endocytosis these clathrin-coated vesicles migrate into the cell where the clathrin coats are lost before delivering their contents to the lysosomes. 

Even if membranous vesicles were commonplace on the early Earth and had sufficient permeability to permit nutrient transport to occur, these structures would be virtually impermeable to larger polymeric molecules that were necessarily incorporated into molecular systems on the pathway to cellular life. The encapsulation of macromolecules in lipid vesicles has been demonstrated by hydration-dehydration cycles that simulate an evaporating lagoon [53] or by freeze-thaw cycles [54]. Molecules as large as DNA can be captured by such processes. For instance, when a dispersion of DNA and fatty acid vesicles is dried, the vesicles fuse to form a multilamellar sandwich structure with... 

Fig. 8 Phase and fluorescence micrographs of membranous vesicular structures formed from a Murchison meteorite extract (left) compared to vesicles formed by a 20 mM de-canoic acid-decanol mixture [72] (center) and a vesicular structure produced by the photoproduct of an interstellar-ice analog [31]. The vesicles produced by the photochemical ice analog product were allowed to capture pyranine, a fluorescent anionic dye, to demonstrate that a true membrane was present. Scale bars show 20, 10, and 5 pm, from left to right...

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