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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We localized myosin in vertebrate nonmuscle cells by electron microscopy using purified antibodies coupled with ferritin. Native and formaldehyde-fixed filaments of purified platelet myosin filaments each consisting of approximately 30 myosin molecules bound an equivalent number of ferritin-antimyosin conjugates. In preparations of crude platelet actomyosin, the ferritin-antimyosin bound exclusively to similar short, 10-15 nm wide filaments. In both cases, binding of the ferritin-antimyosin to the myosin filaments was blocked by preincubation with unlabeled antimyosin. With indirect fluorescent antibody staining at the light microscope level, we found that the ferritin-antimyosin and unlabeled antimyosin stained HeLa cells identically, with the antibodies concentrated in 0.5-microns spots along stress fibers. By electron microscopy, we found that the concentration of ferritin-antimyosin in the dense regions of stress fibers was five to six times that in the intervening less dense regions, 20 times that in the cytoplasmic matrix, and 100 times that in the nucleus. These concentration differences may account for the light microscope antibody staining pattern of spread interphase cells. Some, but certainly not all, of the ferritin-antimyosin was associated with 10-15-nm filaments. In mouse intestinal epithelial cells, ferritin-antimyosin was located almost exclusively in the terminal web. In isolated brush borders exposed to 5 mM MgCl2, ferritin-antimyosin was also concentrated in the terminal web associated with 10-15-nm filaments.
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PMID:Electron microscopic localization of cytoplasmic myosin with ferritin-labeled antibodies. 719 82

An experimental approach is described that enables the analysis of interactions between exogenous surface ligands and components of the cytoplasm in neutrophil leukocytes. Neutrophils treated with the nonionic detergent Lubrol PX, under controlled conditions, yield intact detergent-insoluble ghosts. Morphological analysis of neutrophil ghosts shows that they retain the original dimensions of the cell and consist almost entirely of a peripheral filamentous network, representing the submembranous cortical web, concentric to nuclear remnants. All intracellular membrane-bounded organelles, plasma membrane, and background cytoplasmic electron density are absent. Biochemical analysis of the ghosts shows that less than 10% of enzyme markers for the soluble and granule fractions remain, and that greater than 90% of total cell phospholipid is removed during detergent extraction. The major proteins remaining in the ghosts comigrate, on polyacrylamide gels in the presence of SDS, with chicken gizzard actin, myosin, filamin, and a 110-kdalton protein. Patches and caps induced on neutrophils with either fluorescein isothiocyanate-concanavalin A or ferritin-concanavalin A retain their original location and morphology on ghosts after lysis, as determined by both fluorescence and electron microscopy. In similar experiments, but using 125I-labeled lectins, 37% of total cell bound concanavalin A (Con A) and 25% succinylated Con A remain attached to the ghosts. A major 125I-labeled membrane glycoprotein (80 kdaltons) is associated with ghosts prepared from intact neutrophils iodinated in the presence of exogenous lactoperoxidase. Further 125I-labeled membrane glycoproteins (217, 170, and 147 kdaltons) become associated with ghosts prepared from iodinated cells treated before lysis with Con A, but not with succinylated Con A. These data taken together suggest that linkages exist in neutrophils between proteins exposed on the outer surface of the plasma membrane and the peripheral filamentous network independent of the presence of lipid bilayer. The implications of these findings for surface motile phenomena will be discussed.
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PMID:Transmembrane linkage between surface glycoproteins and components of the cytoplasm in neutrophil leukocytes. 719 81

Terminal webs prepared from mouse intestinal epithelial cells were examined by the quick-freeze, deep-etch, and rotary-replication method. The microvilli of these cells contain actin filaments that extend into the terminal web in compact bundles. Within the terminal web these bundles remain compact; few filaments are separated from the bundles and fewer still bend towards the lateral margins of the cell. Decoration with subfragment 1 (S1) of myosin confirmed that relatively few actin filaments travel horizontally in the web. Instead, between actin bundles there are complicated networks of the fibrils. Here we present two lines of evidence which suggest that myosin is one of the major cross-linkers in the terminal web. First, when brush borders are exposed to 1 mM ATP in 0.3 M KCl, they lose their normal ability to bind antimyosin antibodies as judged by immunofluorescence, and they lose the thin fibrils normally found in deep-etch replicas. Correspondingly, myosin is released into the supernatant as judged by SDS gel electrophoresis. Second, electron microscope immunocytochemistry with antimyosin antibodies followed by ferritin-conjugated second antibodies leads to ferritin deposition mainly on the fibrils at the basal part of rootlets. Deep-etching also reveals that the actin filament bundles are connected to intermediate filaments by another population of cross-linkers that are not extracted by ATP in 0.3 M KCl. From these results we conclude that myosin in the intestinal cell may not only be involved in a short range sliding-filament type of motility, but may also play a purely structural role as a long range cross-linker between microvillar rootlets.
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PMID:Organization of actin, myosin, and intermediate filaments in the brush border of intestinal epithelial cells. 720 10

Recent studies have demonstrated fenestrations in the juxtaglomerular part of the afferent arteriole facing the extraglomerular mesangium and the epithelioid cells in different mammals including humans. The permeability of the endothelium in afferent arteriole may play an important role in various physiologic and pathophysiologic processes. This study therefore was conducted to examine the permeability along the length of afferent arteriole using ferritin particles as an indicator of permeability/fenestration. Assuming the presence of a relationship between the development of permeable endothelial fenestration and renin formation, the permeability of the endothelium and renin granulation and their correlation along the wall of the afferent arteriole under control conditions and during inhibition of renin-angiotensin system by converting enzyme inhibition or AT1 receptor blockade were examined. The intra-aortically administered ferritin particles appeared in the interstitium of the distal part of the afferent arterioles. About one-third to half of the length of the afferent arteriole wall was ferritin-positive. There was a correlation between ferritin-positive and renin-positive portions. The density of ferritin particles was high close to the glomerulus and decreased continuously, similar to the profile of renin distribution. There was also a correlation between ferritin density in basal membrane and the renin granulation index. On the basis of these results, the afferent arteriole, according to its endothelial permeability, can be divided into two distinct portions, i.e., the permeable and the nonpermeable, the length and ratio of which may be related to the actual renin formation. These portions not only are different in the presence or absence of fenestration of the endothelium, but they also show difference in myosin and renin contents, suggesting that each portion may serve different function(s).
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PMID:Endothelial permeability of the afferent arteriole and its changes as the result of alteration in the activity of the renin-angiotensin system. 989 59

The aim of this study was to identify potential protein targets for insulin sensitization in human adipose tissue using unbiased proteomic approaches. Ten moderately obese, but otherwise healthy, subjects were treated with rosiglitazone 4 mg b.i.d. for 14 days and global protein and gene expression changes were monitored. Proteomic analysis revealed distinct up- or downregulation (greater than twofold) in 187 protein spots on the two-dimensional (2-D) gel images between day 0 and day 1 adipose tissue samples. When comparing the protein spots on the gels from day 0 with that of 14-day-treated samples, 122 spots showed differential expression. There was a striking increase in the expression of proteins involved in glucose transporter-4 (GLUT4) granule transport and fusion (actin, myosin-9, tubulin, vimentin, annexins, moesin, LIM, and SH3 domain protein-1), signaling (calmodulin, guanine nucleotide-binding proteins), redox regulation (superoxide dismutase, catalase, ferritin, transferrin, heat shock proteins), and adipogenesis (collagens, galectin-1, nidogen-1, laminin, lamin A/C). However, there was an intriguing absence of correlated changes in mRNA expression, suggesting adaptation at a post-transcriptional level in response to rosiglitazone. Thus, the major changes observed were among proteins involved in cytoskeletal rearrangement, insulin and calcium signaling, and inflammatory and redox signals that decisively upregulate GLUT4 granule trafficking in human adipose tissue. Such orchestrated changes in expression of multiple proteins provide insights into the mechanism underlying the increased efficiency in glucose uptake and improvement of insulin sensitivity in response to rosiglitazone treatment.
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PMID:Proteomic analysis of human adipose tissue after rosiglitazone treatment shows coordinated changes to promote glucose uptake. 1955 78

In this study, suppression subtractive hybridization was used to construct forward and reverse cDNA libraries to identify genes involved in the response of Eisenia fetida after exposure to Escherichia coli O157:H7. We cloned 1428 cDNAs or expressed sequence tags (ESTs), of which 738 were confirmed to be differentially expressed on dot blotting analysis. A total of 394 good-quality ESTs (GenBank dbEST accession numbers HO001170-HO001563) were obtained from the raw clone sequences after cleaning. The genes were associated with metabolism (10%), transport (10%), translation (5%), immunity (2%), and the cytoskeleton (1%). Thirteen candidates were selected to assess expression levels in earthworms exposed to artificially contaminated soil by real-time PCR. The translated amino acid sequences of clones were similar to fibrinolytic protease 1, extracellular globin-3, myosin essential light chain, lumbrokinase, lysozyme, ferritin, ATP synthase F0 subunit 6, and hsp 70. Characterization of differential gene expression in the earthworm E. fetida on exposure to E. coli O157:H7 expands our understanding of the molecular mechanisms of interactions at the earthworm-pathogen interface.
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PMID:Differential expression of genes in the earthworm Eisenia fetida following exposure to Escherichia coli O157:H7. 2118 11

Honeybees (Apis mellifera) form superparamagnetic magnetite to act as a magnetoreceptor for magnetoreception. Biomineralization of superparamagnetic magnetite occurs in the iron deposition vesicles of trophocytes. Even though magnetite has been demonstrated, the mechanism of magnetite biomineralization is unknown. In this study, proteins in the iron granules and iron deposition vesicles of trophocytes were purified and identified by mass spectrometry. Antibodies against such proteins were produced. The major proteins include actin, myosin, ferritin 2, and ATP synthase. Immunolabeling and co-immunoprecipitation studies suggest that iron is stored in ferritin 2 for the purpose of forming 7.5-nm diameter iron particles and that actin-myosin-ferritin 2 may serve as a transporter system. This system, along with calcium and ATP, conveys the iron particles (ferritin) to the center of iron deposition vesicles for iron granules formation. These proteins and reactants are included in iron deposition vesicles during the formation of iron deposition vesicles from the fusion of smooth endoplasmic reticulum. A hypothetical model for magnetite biomineralization in iron deposition vesicles is proposed for honeybees.
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PMID:Identification and localization of proteins associated with biomineralization in the iron deposition vesicles of honeybees (Apis mellifera). 2154 30


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