Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The surface anionic groups of Entamoeba invadens were analysed by cell electrophoresis, by ultrastructural cytochemistry, and by identification of sialic acids using paper and gas-liquid chromatography. Binding of colloidal iron hydroxide (CIH) and of cationized ferritin (CF) particles at pH 1.8 and 7.2, respectively, was observed on the cell surface. E. invadens has a highly negative surface charge (-0.96 microns s-1 V-1 cm). Treatment of the cells with trypsin and neuraminidase significantly reduced the electrophoretic mobility by 24% and 40%, respectively. Treatment of the amoebae with neuraminidase also markedly decreased the binding of CIH to the cell surface. This finding suggests that sialic acid residues are the major anionogenic groups exposed on the surface of E. invadens. Paper and gas-liquid chromatography showed that N-acetylneuraminic acid was the only derivative characterized in E. invadens.
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PMID:Sialic acid is a cell surface component of Entamoeba invadens trophozoites. 273 83

A human hepatic ferritin receptor has been isolated from human liver and has been purified using affinity chromatography. An affinity constant of 6.0 x 10(8) moles-1 liter was determined for the ferritin receptor. The molecular weight was estimated to be approximately 53,000 by gel electrophoresis. Binding of ferritin to the receptor coupled to a microparticulate support was specific for human liver ferritin with no binding of rat or porcine ferritin. Binding was unaffected by a 100-fold excess of human transferrin, human asialoorosomucoid and bovine albumin. After treatment of the receptor protein with trypsin, binding was not detected. The human hepatic ferritin receptor may play an important role in the uptake of iron into the hepatocyte in physiological and pathological conditions.
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PMID:Isolation of a human hepatic ferritin receptor. 283 1

The nature of the adhesive capacity of three hemagglutinating Escherichia coli strains that had earlier been described as nonfimbriated was studied. The strains that were isolated from human disease adhered to human buccal and urinary tract epithelial cells, an adhesion that was not inhibited by D-mannose. By crossed immunoelectrophoresis it was shown that the three strains produced a common antigen, Z1, developed after growth at 37 degrees C but not 18 degrees C. One of the strains produced an additional antigen, Z2, of almost the same electrophoretic mobility in crossed immunoelectrophoresis. A mutant of this strain deficient of its polysaccharide K antigen had maintained the adhesive capacity, indicating that the K antigen was not responsible for adhesion. A further mutant of the acapsular mutant produced a strongly reduced amount of the Z antigens and had lost the ability to adhere. The Z1 (and Z2?) antigens were therefore deemed to be responsible for adhesion. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis of extracts of cells of the three strains, a heavy Coomassie-blue stained line was seen, indicating the presence of a protein subunit of molecular weight slightly above 14,400. By immunoblotting with absorbed antiserum, it was shown that this protein was the same as that detected by crossed immunoelectrophoresis. Protease from Streptomyces griseus, but not trypsin, digested the protein. Heating to 100 degrees C did not affect it. By immunoelectron microscopy of embedded and sectioned bacteria that had first been treated with specific antisera and ferritin-labeled antirabbit immunoglobulin, the protein adhesin-antibody complex was found to surround the bacteria as a heavy capsule. After negative staining with uranylacetate (pH approximately 4), the capsule appeared as a mesh of very fine filaments. The possible role of this capsule in the pathogenesis of disease is discussed.
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PMID:An adhesive protein capsule of Escherichia coli. 285 13

The domain organization of the zymogen subunits of the first component of human complement C1s, C1r2 and the complex C1s-C1r2-C1s was studied by electron microscopy. In the absence of Ca2+, monomeric C1s was visualized as a dumb-bell-shaped molecule consisting of two globular domains (center-to-center distance 11 nm) connected by a rod. One of the globular domains is assigned to the light chain (B-chain) of the activated molecule, which is homologous to trypsin and other serine proteases. The second globular domain and the rod are assigned to the heavy chain (A-chain) of CIs. The subunit C1r is a stable dimer in the presence or absence of Ca2+. This dimer C1r2 was visualized as composed of two dumb-bells of dimensions similar to those observed for C1s. These are connected near the junctions between the rod and one of the globular domains. This leads to the structure of an asymmetrical X with two inner closely spaced globules (center-to-center distance 7 nm) and two outer globules at a larger distance (14 nm). By comparison with fragment C1rII2, in which part of the A-chain is removed, the inner globular domains were assigned to the catalytic B-chains. This characteristic structure of C1r2 is readily recognized in the central portion of the thread-like 54 nm long C1s-C1r2-C1s complex formed in the presence of Ca2+. By affinity-labeling of C1s with biotin and visualization of avidin-ferritin conjugates in the reconstituted complex, it was demonstrated that C1s forms the outer portion of the complex. A detailed model of C1s-C1r2-C1s is proposed, according to which two C1s monomers bind to the outer globes of C1r2 by contacts between their heavy chains and those of C1r. According to this model the catalytic domains of C1r are located in the center and those of C1s at the very tips of the C1s-C1r2-C1s complex. On the basis of the structure of C1s-C1r2-C1s, we derived a detailed model of the C1 complex (composed of C1q and the tetrameric complex) and we discuss this model with a view to finding a possible activation mechanism of C1.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Functional model of subcomponent C1 of human complement. 302 30

The location of lipoteichoic acid (LTA) on the surface of group A streptococci was studied by immunoelectron microscopic and ultrastructural cytochemical methods, i.e. by means of LTA antibodies labelled with ferritin, or concanavalin A labelled with ferritin or colloidal gold. All these methods proved the LTA to be located on the outer cell surface of most group A streptococcus strains. The differences in the intensity of labelling paralleled the hydrophobicity of the strains, being substantially higher in the strains exhibiting a high degree of hydrophobicity. Treatment of streptococci with pronase or trypsin led to a complete loss of surface-located LTA. On the other hand, pepsin treatment of streptococci under mild conditions resulted in an increased amount of surface-located LTA in some strains. On the isolated cell walls, LTA could be demonstrated only on the outer surface of the walls. These findings correlated well with the presumed role of group A streptococcus LTA in the adherence of streptococci to the epithelial cells which is accomplished with the aid of surface-located LTA molecules.
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PMID:Electron microscopic localization of lipoteichoic acid on group A streptococci. 305 68

The surface charge of epimastigote and trypomastigote forms of Trypanosoma cruzi was analysed by three approaches: a) visualization by electron microscopy of the binding of cationic particles (cationized ferritin at pH 7.2 and colloidal iron hydroxyde at pH 1.8) to the parasite's surface, b) visualization of the binding of fluorescein-labeled lectins (PNA and LPA) to the parasite's surface, and c) by cell electrophoresis. In all cases control, trypsin and neuraminidase-treated cells were analysed. The results obtained indicate that sialic acid residues located on the parasite's surface are responsible for the binding of cationic particles to it and the major component responsible for the net negative surface charge presented by T. cruzi. Phosphate groups, associated to phospholipids, also contribute to the negative surface charge. The effect of previous incubation of the parasites in the presence of lectins (ConA, WGA, PNA, RCA and LPA) on their surface charge was also analysed by cell electrophoresis.
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PMID:The surface charge of Trypanosoma cruzi: analysis using cell electrophoresis, lectins and ultrastructural cytochemistry. 309 34

The biological activity and morphological distribution of protein A on the cell surface were studied in a medium containing an excess of either mannitol or glucose, which suppressed protein A production of Staphylococcus aureus, Cowan I strain. Preculture of the organisms in the presence of a sugar suppressed the expression of protein A, resulting in a decrease in the number of cells bound with antiferritin rabbit IgG molecules, which specifically indicate protein A distribution. The distribution pattern of protein A on the cell surface changed with glucose but not with mannitol. The two-layered ferritin distribution on the organism grown in the control medium was altered into a heavily labeled, thick and rough layer with glucose, suggesting the induction of a conformational change in the polypeptide chain forming protein A. This was positively supported by the increase in trypsin susceptibility of protein A.
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PMID:Effect of mannitol and glucose on the distribution and trypsin susceptibility of protein A of Staphylococcus aureus. 309 33

Rabbit muscle phosphoglucomutase was irreversibly inactivated upon preincubation with vitamin C (Vit C). Fe(III), NADH.NADH oxidase.Fe(III), or ferritin.Vit C. Substrate, glucose 1-phosphate and Mg2+ afforded partial protection. No altered amino acid could be detected in the inactive enzyme. Enzyme so inactivated was more susceptible to trypsin. More importantly, during inactivation, the enzyme lost up to 70% of its enzyme-bound phosphate; the completely inactivated enzyme retained the remainder of the bound phosphate which was isolatable as phosphoserine residing in the 22-amino acid long tryptic peptide. Free phosphoserine as well as those in phosphorylase alpha and phosphocasein were resistant to the oxidizing system, suggesting that the phosphoserine of phosphoglucomutase is uniquely vulnerable to these treatments. Alternatively, a fraction of the total 1 mol of phosphate in the phosphoform of phosphoglucomutase may not be associated with phosphoserine. Phosphoglyceromutase, which has phosphohistidine at its active site, was also inactivated by the oxidizing system. However, it did not release any of the bound phosphate.
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PMID:Vit C.Fe(III) induced loss of the covalently bound phosphate and enzyme activity of phosphoglucomutase. 315 31

The IgG-Fc binding activity and binding sites on the cell surface of streptococci, strains AR1 (group A) and G148 (group G), and Staphylococcus aureus strain Cowan I were examined by hemagglutination (HA) and immunoelectron microscopic methods. No distinct difference was observed in the HA activity among these three strains. However, the strains differed in the distribution of Fc receptor. Cowan I cells (having protein A) were heavily covered with two layers of ferritin particles, whereas AR1 cells were heavily covered with a single, rough layer of ferritin particles. G148 cells (having protein G) were labeled with a relatively thin, rough ferritin layer. The trypsin susceptibility of the Fc receptors of the AR1 strain was much higher than that of the G148 strain. These results suggest that both streptococcal strains are distinctly different in the arrangement or in the conformation of the Fc receptor from the Cowan I strain. It is also suggested that the Fc receptor molecules of the streptococcal strains differ from each other not only in conformation but also in trypsin susceptibility.
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PMID:Hemagglutination activity and localization of Fc receptor of group A and G streptococci. 328 3

The fine structure of the Staphylococcus aureus cell wall was determined by electron microscopy with the new technique of rapid freezing and substitution fixation. The surface of the cell wall was covered with a fuzzy coat which consisted of fine fibers or an electron-dense mass. Morphological examination of the cell wall, which was treated sequentially with sodium dodecyl sulfate, trypsin, and trichloroacetic acid, revealed that this coat was partially removed by trypsin digestion and was completely removed by trichloroacetic acid extraction but was not affected by sodium dodecyl sulfate treatment, suggesting that the fuzzy coat consists mostly of a complex of teichoic acids and proteins. This was confirmed by the application of the concanavalin A-ferritin technique for teichoic acid and antiferritin immunoglobulin G technique for protein A.
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PMID:Structure of the Staphylococcus aureus cell wall determined by the freeze-substitution method. 358 61


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