Cytoskeletal structures

Hryant Does that mean it is associated with a membrane protein Then, when you go to the apical crescent stage is that apical crescent membrane-associated, or is it a cytoskeletal structure ... 

Hecht G, C Pothoulakis, JT LaMont, JL Madara. (1988). Clostridium difficile toxin A perturbs cytoskeletal structure and tight junction permeability of cultured human intestinal epithelial monolayers. J Clin Invest 82 1516-1524. 

CYTOSKELETAL STRUCTURES IN THE NEURON HAVE COMPLEMENTARY DISTRIBUTIONS AND FUNCTIONS 132... 

Proteins of the cytoskeleton play a central role in the creation and maintenance of cell shapes in all tissues. They serve multiple roles in eukaryotic cells. First, they provide structural organization for the cell interior, helping to establish metabolic compartments. Second, cytoskeletal structures serve as tracks for intracellular transport, which creates and maintains differentiated cellular functions. Finally, the cytoskeleton comprises the core framework of cellular morphologies. 

Methods for visualizing individual neurons and glia in vivo have depended for more than 100 years on histo-chemical reactions with cytoskeletal elements and even now these methods have not been surpassed. Because cytoskeletal structures play a particularly prominent role in the nervous system, cytoskeletal proteins represent a large fraction of total brain protein, comprising perhaps a third or more of the total. In fact, much of our knowledge about cytoskeletal biochemistry is based on studies of proteins purified from brain. The aims of this chapter are twofold first to provide an introduction to the cytoskeletal elements themselves and second to examine their role in neuronal function. Throughout, the emphasis will be on the cytoskeleton as a vital, dynamic component of the nervous system. 

The nervous system contains an unusually diverse set of intermediate filaments (Table 8-2) with distinctive cellular distributions and developmental expression [21, 22]. Despite their molecular heterogeneity, all intermediate filaments appear as solid, rope-like fibers 8-12 nm in diameter. Neuronal intermediate filaments (NFs) can be hundreds of micrometers long and have characteristic sidearm projections, while filaments in glia or other nonneuronal cells are shorter and lack sidearms (Fig. 8-2). The existence of NFs was established long before much was known about their biochemistry or properties. As stable cytoskeletal structures, NFs were noted in early electron micrographs, and many traditional histological procedures that visualize neurons are based on a specific interaction of metal stains with NFs. 

Not all neurons have NFs. Indeed, one entire phylum in the animal kingdom, arthropods, expresses only type V nuclear lamins so arthropod cells have no IF cytoskeletal structures at all. In addition, mature oligodendrocytes lack IFs although their embryonic precursors contain vimentin. Clearly, the IFs are not essential for cell survival. Yet, in large myelinated fibers, NFs make up the bulk of axonal volume and represent a substantial fraction of the total protein in brain. In most organisms, IFs in both glia... 

In some cases, the primary pathogenic mechanism is an effect on one or more cytoskeletal structures. For example, some widely used chemotherapeutic agents for treatment... 

The macroscopic rates measured by radiolabel experiments should not be taken to reflect maximum rates of the motors involved. As with mitochondrial transport, the net rate of slow component proteins reflects both the rate of actual movement and the fraction of a time interval that a structure is moving. The elongate shape of cytoskeletal structures and their potential for many interactions means that net displacements are discontinuous. If a structure is moving at a speed of 2 j,m/s, but on average only moves at that rate for one second out of every 100 seconds, then the average rate for the structure will translate to a net rate of only 0.02 pm/s [31]. 

However, 2 also affected the regulation of actin stress fiber formation [19]. Rho proteins are involved in the regulation of various cytoskeletal structures, and RhoB is believed to be one of the prime targets of FTase inhibitors. Rho B is apparently both geranylgeranylated and farnesylated [20, 21]. If cells were treated with 2, vesicular localization of Rho B was inhibited. Thus 2 may also inhibit the farnesylation of Rho B, thereby interfering with actin stress fiber formation [22]. 

Changes in cytoskeletal structure during chemotaxis and phagocytosis... 

High-contrast visualization of submembrane cytoskeletal structure on... 

The work that follows pertains primarily to actin networks. Many proteins within a cell are known to associate with actin. Among these are molecules which can initiate or terminate polymerization, intercalate with and cut chains, crosslink or bundle filaments, or induce network contraction (i.e., myosin) (A,11,12). The central concern of this paper is an exploration of the way that such molecular species interact to form complex networks. Ultimately we wish to elucidate the biophysical linkages between molecular properties and cellular function (like locomotion and shape differentiation) in which cytoskeletal structures are essential attributes. Here, however, we examine the iri vitro formation of cytoplasmic gels, with an emphasis on delineating quantitative assays for network constituents. Specific attention is given to gel volume assays, determinations of gelation times, and elasticity measurements. 

Lelivelt MJ, Culbertson MR (1999) Yeast Upf proteins required for RNA surveillance affect global expression of the yeast transcriptome. Mol Cell Biol 19 6710-6719 Lenk R, Ransom L, Kaufmann Y, Penman S (1977) A cytoskeletal structure wifii associated polyribosomes... 

Fig. 17 Association of hydrogenosomes and microtubules in T. foetus, a Thin section of hydrogenosomes (H) in close proximity with microtubules (asterisks), b Freeze-etching after quick-freezing and rotatory shadowing showing a hydrogenosome in close association with cytoskeletal structures, probably microtubules. Bars = 200 nm. (Benchimol, unpublished)...

Lipids and proteins can diffuse laterally within the plane of the membrane, but this mobility is limited by interactions of membrane proteins with internal cytoskeletal structures and interactions of lipids with lipid rafts. One class of lipid rafts consists of sphingolipids and cholesterol with a subset of membrane proteins that are GPI-linked or attached to several long-chain fatty acyl moieties. 

Mangeat, P. H., and Burridge, K. (1984). Immunoprecipitation of nonerythrocyte spectrin within live cells following microinjection of specific antibodies Relation to cytoskeletal structures./ Cell. Biol. 98, 1363-1377. 

Papp, Z., van der Velden, J., Stienen, G.J., 2000, Calpain-I induced alterations in the cytoskeletal structure and impaired mechanical properties of single myocytes of rat heart,. Cardiovasc. Res., 45, 981-993... 

Lakkakorpi PT, Lehenkari PP, Rautiala TJ, Vaananen HK. 1996. Different calcium sensitivity in osteoclasts on glass and on bone and maintenance of cytoskeletal structures on bone in the presence of high extracellular calcium. J Cell Physiol 168 668-77. 

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