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

Two improved procedures were developed for activating ferritin so that the ferritin could be covalently linked to antibodies. One procedure involved use of a water-soluble carbodiimide and N-hydroxysuccinimide to prepare ferritin-containing activated esters. The other involved activation of the ferritin with excess glutaraldehyde. The ferritin-antibody conjugates prepared with the two procedures were shown to have a number of properties which made them suitable for locating antigenic components in cells.
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PMID:Two improved methods for preparing ferritin-protein conjugates for electron microscopy. 80 73

The detailed reversible binding isotherms of sodium dodecyl sulfate (NaDodSO4) with 13 different initially native proteins are reported; the data were obtained at 20 degrees C and pH 7.1, ionic strength 0.033, with amounts bound with some proteins up to 1.1 g per g of protein. Although the isotherms of some of the proteins do not vary widely, extreme variations between certain classes are found. Thus, for example, hemoglobin and myoglobin both have high affinities and high binding capacities, while gamma-globulin, apoferritin, and transferrin have low initial affinities, and change drastically at higher concentrations. The protein-NaDodSO4 complexes solubilize the water-insoluble dye dimethylaminoazobenzene (DMAB) as effectively as micelles of pure NaDodSO4 when only small amounts (0.2 to 0.5 g/g of NaDodSO4) are bound. In most cases this effectiveness falls progressively as larger amounts are bound, and may even cease altogether at limits characteristic of the individual protein. With some of the latter, a second region of renewed solubilization occurs when substantially higher amounts of NaDodSO4 are present. In all cases, solubilization by ordinary micelles in normal amount occurs when the free NaDodSO4 concentration exceeds the critical micelle concentration, but the binding of NPADodSO4 to the protein also increases, in competition with formation of micelles. With some, but not all proteins the NaDodSO4 bound at concentrations above the cmc also solubilizes DMAB. In such cases the solubilizations by the protein-NaDodSO4 complexes and by the simple micelles are additive. The significance of the differences in binding and solubilizing encountered among these proteins is discussed in terms of surface structure, cooperativity of binding, and protein composition. No certain correlations with content of most amino acids, subunit structure, solubility, and hydrophobicity have been found, but there is a weak inverse dependence of solubilizing effectiveness on molecular size and indications of a strong dependence on content of cationic groups.
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PMID:Differences in the solubilizing effectiveness of the sodium dodecyl sulfate complexes of various proteins. 83 11

The water-soluble carbodiimide, 1-cyclohexyl-3-(2-morpholinoethyl)-carbodiimide metho-p-toluenesulfonate, has been used to couple horse ferritin covalently to formalin-fixed, human red blood cells. This method has been optimized with respect to sensitivity, range, and reproducibility. The sensitized cells are stable for at least 6 months at 4 degrees C, and they may be stored frozen without additives or special precautions. Titers of 1/216 are routinely obtained with antisera to ferritin.
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PMID:Carbodimide coupling to formalin-fixed red blood cells. A direct passive hemagglutination test for anti-horse ferritin. 93 49

The carbohydrate rich filamentous coat investing the mature Schistosoma manosini cercaria affects important physiological and antigenic properties of the larval body surface. The origin of the filamentous coat and intrinsic topochemical properties of ccrcariae were investigated by fine structural and cytochemical examination of intrasporocyst larvae of various developmental stages. Staining results achieved with concanavalin A-peroxidase, bismuth subnitrate, silver protein, cationic colloidal iron, and polycationic ferritin indicate the presence of both neutral and acidic glycans at the external surface of the trilaminar tegumental plasmalemma, the latter saccharide moieties conferring upon this surface a superficial electronegative charge. The filamentous coat, apparent only on relatively well-developed larvae, is rich in neutral glycans, but fails to stain with cationic cytochemical reagents. Appearance of the surface coat occurs coincident with the differentiation of tegumentary cytons, the elaboration of carbohydrate-containing vesicles by Golgi complexes within these cell bodies, and the translocation of vesicles from sites of formation to the tegumental syncytium. It is likely that those saccharides, glycoproteins, and/or glycolipids present within the neutral filamentous coat, and those which constitute the acidic layer immediately superticial to the larval body surface, are intrinsic molecular constituents of the cercarial tegumental plasmalemma. Both the neutral filamentous coat and subjacent acidic layer may be regarded as distinct functional elements of the larval body surface glycocalyx. The molecular architecture of this membrane complex apparently reflects the specializations necessary for survival in fresh water followed by rapid adaptation to the serum environment of the mammalian host.
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PMID:Schistosoma mansoni: topochemical features of intrasporocyst cercariae. 100 81

By means tracer substances (horseradish peroxidase, ferritin) the permeability of human amnion and umbilical cord (2. to 6. lunar month) has been investigated ultrastructurally. The structure of intercellular cleft permits a passiv transfer of the water and electrolytes in both ways. The findings indicated, that the passage of proteins with a molecular weight of peroxidase predominantly takes place through the intercellular clefts less by means of pinocytosis. Ferritin particles can not penetrate. The epithelium of umbilical cord seems to play no special role in protein and water transport. The results were discussed.
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PMID:[Ultrastructural studies on the permeability of the amnion-epithelium for peroxidase and ferritin. Contribution on paraplacental metabolism]. 102 May 13

The structural basis of the permeability barrier in mammalian epidermis was examined by tracer and freeze-fracture techniques. Water-soluble tracers (horesradish peroxidase, lanthanum, ferritin) were injected into neonatal mice or into isolated upper epidermal sheets obtained with staphylococcal exfoliatin. Tracers percolated through the intercellular spaces to the upper stratum granulosum, where further egress was impeded by extruded contents of lamellar bodies. The lamellar contents initially remain segregated in pockets, then fuse to form broad sheets which fill intercellular regions of the stratum corneum, obscuring the outer leaflet of the plasma membrane. These striated intercellular regions are interrupted by periodic bulbous dilatations. When adequately preserved, the interstices of the stratum corneum are wider, by a factor of 5-10 times that previously appreciated. Freeze-fracture replicas of granular cell membranes revealed desmosomes, sparse plasma membrane particles, and accumulating intercellular lamellae, but no tight junctions. Fractured stratum corneum displayed large, smooth, multilaminated fracture faces. By freeze-substitution, proof was obtained that the fracture plane had diverted from the usual intramembranous route in the stratum granulosum to the intercellular space in the stratum corneum. We conclude that: (a) the primary barrier to water loss is formed in the stratum granulosum and is subserved by intercellular deposition of lamellar bodies, rather than occluding zonules; (b) a novel, intercellular freeze-fracture plane occurs within the stratum corneum; (c) intercellular regions of the stratum corneum comprise an expanded, structurally complex, presumably lipid-rich region which may play an important role in percutaneous transport.
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PMID:The permeability barrier in mammalian epidermis. 112 9

To investigate the permeability properties of the basement membrane beneath macula densa cells and between extraglomerular mesangial cells, thick ascending limbs with attached glomeruli were dissected from rabbit kidney and incubated in a Ringers solution containing either horseradish peroxidase (HRP) (1 mg/ml; molecular weight approximately 40,000) or native or cationic ferritin (both at 5 mg/ml molecular weight approximately 450,000) for 5 and 20 min at room temperature. Tubules were processed for electron microscopy. At both time points, HRP reaction product fully permeated the matrix material between extraglomerular mesangial cells, the basement membrane underneath the macula densa, and also was occasionally located in intercellular spaces and intracellular vesicles within macula densa cells. Similar results were obtained with native and cationic ferritin. In separate experiments, thick ascending limbs with attached glomeruli were perfused for 20 min at room temperature with a Ringer solution containing HRP (1 mg/ml). HRP was found in tubulovesicular bodies within the apical cytoplasm of macula densa cells again indicating that these cells exhibit endocytotic activity. However, HRP did not gain access to intercellular spaces indicating that the apical junctional complex was impermeable to HRP. These results demonstrate that the macula densa basement membrane and matrix material between extraglomerular mesangial cells is permeable to high molecular weight molecules and suggest unhindered diffusion of water and solutes within this area.
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PMID:Permeability of the macula densa basement membrane area to high molecular weight molecules. 137 68

To examine the influence of erythropoiesis on iron absorption, radioiron absorption tests were performed in normal subjects before and after a course of recombinant erythropoietin. The absorption of heme and nonheme iron from a standard meal was measured in nine subjects, and the absorption of a therapeutic dose of ferrous sulfate given with or without food was determined in an additional 11 subjects. The subcutaneous administration of 100 U recombinant human erythropoietin/kg body weight given on 10 successive days over a 2-week period induced a brisk increase in erythropoiesis and a sharp decrease in iron stores. With the standard meal, there was a modest increase in heme iron absorption from 47.0% to 58.6% (p < 0.05) and a dramatic five-fold rise in nonheme iron absorption from 5.9% to 31.8% (p < 0.001). The absorption of 50 mg iron as ferrous sulfate increased from 2.0% to 17.9% when given with food (p < 0.001) and from 7.0% to 24.6% when given with water (p < 0.001). To assess the effect of erythropoiesis independently of the induced changes in iron status, the absorption data were adjusted to a common serum ferritin level. The relative increase in iron absorption was still significant for both dietary nonheme iron (ratio 2.51, p < 0.02) and ferrous sulfate given with food (ratio 2.99, p < 0.01). It is concluded that the striking enhancement of iron absorption following regular erythropoietin administration in normal subjects is related to the combined effect of diminished iron stores and augmented erythropoiesis.
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PMID:Effect of enhanced erythropoiesis on iron absorption. 143 4

Immunohistochemistry for rat liver ferritin (FRT) revealed an intensive labeling in some structures of the rat brain. In the supraoptic (SON) and paraventricular (PVN) hypothalamic nuclei, almost all neurosecretory neurons with vasopressin (AVP)-like immunoreactivity were immunostained with FRT. After water deprivation, a marked enlargement of cell body and an immunoreactivity to transferrin receptors were found in AVP-, FRT- and double (AVP+FRT)-labeled neurons in the SON and PVN.
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PMID:Magnocellular neurosecretory neurons with ferritin-like immunoreactivity in the hypothalamic supraoptic and paraventricular nuclei of the rat. 147 32

Measurements of nutritionally relevant biochemical and endocrine variables were made on 60 apparently healthy children (group A) whose parents suffered from leprosy and who had been separated at the age of 4 years and brought up in preventoria. Most of the measurements were also made on a comparison group of healthy children from the same poor socio-economic class (group B). In both groups the serum concentrations of cholesterol and triglycerides were well below those found in Western populations. Almost all the children in both groups were anaemic, but serum iron and ferritin levels were satisfactory. Folate and vitamin B12 levels were measured in group A only and were low in a significant proportion. Deficiency of these water-soluble vitamins may be a cause of the anaemia. Low albumin levels were found in 40% of group A children, compared with 2% in group B. The concentrations of calcium and magnesium were lower and that of phosphate higher in group A than in B. In both groups one-third of the children had low levels of serum zinc. Fifteen per cent of group A children had biochemical evidence of vitamin A deficiency, but none were deficient in vitamin E. Levels of total T3 and total T4 were below the lower limit of normal in a substantial proportion of children in both groups. Concentrations of parathyroid hormone were increased in parallel with the low values for serum calcium. Radiological studies of ossification centres in 57 group A children showed delayed maturation in 11 cases. The relevance of these findings to previous studies of the children of lepers in India is discussed.
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PMID:Nutritional status of children of urban leprosy patients staying at preventoria based on biochemical parameters. 148 18


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