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

alpha-Actinin isolated from dog muscle was used to incite antibodies in rabbits, Antibodies, purified by affinity chromatography on CNBr-Sepharose coupled with alpha-actinin and then ferritin-labeled were found to localize on the Z disc of muscle sarcomeres. Molecules of alpha-actinin as an adsorbed monolayer on the surface of polystyrene Lytron particles could bind muscle-actin and tropomyosin from solution. Both the ATPase activity and superprecipitation of an erythrocyte-actin and muscle-myosin hybrid actomyosin complex were altered by alpha-actinin, while tropomyosin diminished these alpha-actinin effects. The binding properties of alpha-actinin are consistent with those of an anchoring protein for microfilaments in nonmuscle cells.
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PMID:alpha-Actinin and tropomyosin interactions with a hybrid complex of erythrocyte-actin and muscle-myosin. 14 86

Spectrin, a protein complex which is peripherally attached to the cytoplasmic surface of the human erythrocyte membrane, cannot be detected (by complement fixation with anti-spectrin antibodies) in homogenates of several different human non-muscle cells studied. On the other hand, a protein antigenically identical or similar to human smooth muscle myosin was detected (by complement fixation with antibodies to uterine smooth muscle myosin) in these cells. In the case of human fibroblast line WI38, this smooth muscle myosin like component was shown (by ferritin-antibody experiments in electron microscopy) to be at least partly associated with cytoplasmic surface of the plasma membrane of the cell. It is proposed that the spectrin complex of the erythrocyte membrane and the smooth muscle myosin-like component of the fibroblast membrane play similar roles in regulating the translational mobilities of integral proteins in their respective membranes.
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PMID:Detection and ultrastructural localization of human smooth muscle myosin-like molecules in human non-muscle cells by specific antibodies. 105 11

Cell-surface IgM (antigen receptor) sediments with the membrane fraction following osmotic lysis and homogenization of cells of the human lymphoblastoid cell line WiL2. In nonreducing buffers, SDS PAGE analysis of membrane pellets demonstrates that "native" membrane IgM exists as a dimer. In contrast to osmotic lysis, lysis of cells with the nonionic detergent Triton X-100 releases approximately 90% of the membrane-bound IgM into the supernatant; approximately 10% of the IgM pellets with the cytoskeletal fraction on centrifugation. Ligand challenge with either mu-chain-specific antibodies or concanavalin A induces a change in the state of membrane IgM making it refractory to detergent extraction, such that 43% of the IgM pellets during centrifugation. This ligand-induced retention of IgM is significantly diminished by the microfilament-disrupting agent cytochalasin D, whereas pretreatment of cells with sodium azide or colchicine results in no significant change in the percentage of membrane IgM retained by Triton X-100 residues. These results indicate that retention of IgM involves an association with the cortical actin-based cytoskeleton. Investigation of the structural basis for ligand-induced Triton X-100 retention of membrane IgM by using ferritin-conjugated antibodies, myosin subfragment S1, and stereo-imaging electron microscopy has revealed linkages between ligand-receptor (antigen-IgM) complexes and elements of the cortical actin-based cytoskeleton.
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PMID:Membrane IgM: interactions with the cortical cytoskeleton in the human lymphoblastoid cell line WiL2. 316 34

Outer hair cell (OHC) shortening has previously been induced in vitro by the application of solutions containing high potassium (a depolarizing agent), acetylcholine (a suggested efferent transmitter) and cationized ferritin (a positively charged macromolecule), as well as by electrical current. The application of caffeine, which causes contractures in skeletal and smooth muscle by releasing calcium from intracellular stores to activate actin and myosin interaction, also causes shortening of OHCs. Tetracaine, which interferes with calcium movement in muscle and non-muscle cells, blocks potassium-induced and caffeine-induced shortening of OHCs, but does not block electrically-induced shortening. Sodium dantrolene which is an inhibitor of intracellular calcium release in skeletal muscle does not block potassium-induced OHC shortening. Immunocytochemical studies using antibodies to muscle-like contractile and regulatory proteins on unfixed, freeze-dried OHCs demonstrate the co-localization of calmodulin with actin throughout the OHC cytoplasm. These results support the ideas that in OHCs, intracellular calcium release is involved in the activation of shortening and that an actin-mediated cell shape change may be regulated by calmodulin in a manner similar to that which occurs in contraction of smooth muscle.
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PMID:Effects of caffeine and tetracaine on outer hair cell shortening suggest intracellular calcium involvement. 335 Jul 71

A procedure has been developed for the immunoelectron microscopic localization of intracellular antigens on thin-sectioned tissues. The tissues were fixed in a periodate-lysine-paraformaldehyde solution or a formaldehyde-glutaraldehyde combination and embedded in the acrylate-methacrylate mixture, Lowicryl K4M (Polaron), which was polymerized under ultraviolet irradiation at -35 degrees C. Thin sections were mounted on gold grids, immunostained using an indirect method with ferritin-labeled antibodies, and, optionally, counterstained with osmium tetroxide and/or lead citrate and uranyl acetate. The procedure provided good morphologic preservation of the cell architecture in adult and embryonic heart, and skeletal and smooth muscle tissue, as well as nonmuscle cells. At the same time it retained the antigenicities of several contractile proteins, including myosin, tropomyosin, actin, and alpha-actinin. The method has advantages over en bloc staining techniques in that the problem of antibody penetration into the cells is eliminated and careful controls can be performed on adjacent sections. This technique will be useful for localizing, at the ultrastructural level, contractile and other selected proteins in a variety of muscle and non-muscle cells. Details of the new protocol and a description of the results of using antibody against the contractile protein, alpha-actinin, are given.
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PMID:Immunoelectron microscopic localization of alpha-actinin on Lowicryl-embedded thin-sectioned tissues. 388 38

The cytological organization of flight muscle fibers of Odonata has been investigated. These fibers, in representatives of the Zygoptera and Anisoptera, have been compared and found to be similar, except that, in the former, pairs of lamellar fibrils, rather than single fibrils, alternate with the mitochondria. In each instance, in these synchronous muscles, the actin filaments of the myofibrils are found to lie opposite to and midway between pairs of myosin filaments-a configuration previously reported in asynchronous flight muscle fibers. The disposition of the T system and sarcoplasmic reticulum membranes in glutaraldehyde-fixed anisopteran muscle is described in detail: the T system tubules are shown to be radially continuous across the fiber, and are derived as openmouthed invaginations from the surface cell-membrane. The detailed organization of the dyad junctions between these tubules and the adjoining cisternae of the sarcoplasmic reticulum is described. The accessibility of the T system interior to diffusion exchange with the general extracellular milieu has been investigated by studies on the penetration of ferritin into the fiber: molecules of this marker have been found to diffuse solely along the T system tubules, and their presence in the tubule extremities adjoining the centrally placed nuclei confirms the morphological evidence suggesting that these tubules provide open diffusion channels extending across the radius of the fiber. The possible physiological role of these membrane components and their distribution in synchronous muscles of insects and vertebrates and in asynchronous insect flight muscle are discussed.
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PMID:The organization of flight muscle fibers in the Odonata. 590 94

Microtubules have been classified as either stable or labile, according to their resistance towards depolymerizing agents. The highest stability belongs to those organized in composite structures, in which many other proteins are associated with the tubulin. Among these microtubular systems, the marginal band of amphibian erythrocytes is unusually stable. This system can be readily isolated from Triturus red blood cells, and therefore lends itself very readily to ultrastructural and biochemical analyses. Immunofluorescence and electrophoretic analyses of the isolated bands reveal 14 components, among which tubulin, actin, myosin and a 90K glycoprotein were identified. Tannic acid-glutaraldehyde fixation reveals a conspicuous opaque material surrounding the microtubules. Cationized ferritin binding suggests the presence of anionic sites. Moreover, neuraminidase causes the disorganization of the microtubule-associated opaque material. The 90K glycoprotein is presumed to be related to the unusual stability of the microtubular system forming the marginal band.
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PMID:Observations on the molecular components stabilizing the microtubular system of the marginal band in the newt erythrocyte. 676 28

Serial sectioning and immuno-ferritin plus peroxidase labeling of ultrathin frozen sections have been used for the simultaneous localization at the electron microscopic level of surface concanavalin A (Con A) receptors and the intracellular contractile protein, myosin, in mouse splenic lymphocytes. An accumulation of intracellular myosin directly underneath the Con A-induced receptor clusters has been observed. This myosin accumulation seems to be restricted to within approximately 1,000-1,500 A from the surface of the cell. This result provides additional support for the possible occurrence of transmembrane interactions between surface receptors and intracellular contractile elements.
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PMID:Simultaneous localization of intracellular myosin and surface concanavalin A receptor clusters using immuno-electron microscopy. 699 97

In the light microscope two types (I, II) of skeletal muscle fibres can be distinguished with antibodies against myosin isozymes. At the ultrastructural level a difference in Z-line width has led to muscle fibre classification. In this study we distinguish at the ultrastructural level between type I and type II fibres of the M. soleus and M. plantaris of adult mice using ultracryosections with immuno-ferritin and antisera against myosin isozymes. Muscle fibres of the M. plantaris are identified as type II fibres and the fibres of the M. soleus are divided in type I and type II fibres. In the immunologically identified fibres the filament overlap in the Z-line was measured. The type II fibres of the M. plantaris have narrow Z-lines, whereas type I and type II fibres of the M. soleus have wide Z-lines. We conclude that a classification of fibres based on Z-line width differs from the type I/type II classification. The antimyosin antibodies react exclusively with the A-band. In serial sections the myosin isozymes can be identified unambiguously. This is a prerequisite for further studies of myosin isozyme distribution in "mixed" muscle fibres.
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PMID:Myofibrillar differences among mammalian skeletal muscle fibres at the ultrastructural level. A comparison of immunocytochemical and morphometrical parameters. 700 73

Nonmuscle myosin in the cytoplasm of cultured fibroblastic cells has been localized using light and electron microscopic immunocytochemistry. Antibodies to purified fibroblast myosin were produced in goat and rabbit and purified by affinity chromatography. Light microscopic immunofluorescence localization showed patterns similar to those previously published. Electron microscopic localization using the ethyldimethyl aminopropyl carbodiimide-glutaraldehyde-saponin (EGS) fixation-permeabilization procedure and the ferritin bridge localization method produced quantifiable localization in intracellular sites with well-preserved ultrastructural morphology. Myosin was found to be a major component of the cytosol. It was distributed diffusely with no preferential localization on membranous organelles. Myosin was found to be slightly concentrated on the surface of microfilament-containing structures, including the subplasmalemmal microfilament mat and stress fibers, occasionally with an interrupted periodicity. However, no myosin was found in surface ruffles or microvilli. Morphometric quantitation showed that the majority of the cell's myosin was in the cytosol. This location is compatible with myosin being a component of the microtrabecular lattice of the cytoplasmic ground substance. The concentration of myosin in association with microfilaments was only twice that of the cytosol. This interpretation must be somewhat tempered by the possibility that some myosin bound to tightly packed actin may be inaccessible. The significance of this distribution of myosin in cell function is discussed.
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PMID:Ultrastructural immunocytochemical localization of myosin in cultured fibroblastic cells. 703 61


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