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)

We have studied iron transfer from transferrin to ferritin in the presence of ATP, GTP, ADP, AMP and 2,3-diphosphoglycerate. These compounds, with the exception of AMP, can release iron from transferrin at pH 7.4 and form a stable Fe(III)-phosphate complex. From these complexes, only a limited number of Fe(III) atoms can be incorporated into ferritin. Ascorbate enhances iron transfer from transferrin to ferritin at the beginning of the process but subsequently inhibits further iron deposition in ferritin.
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PMID:Iron transfer form transferrin to ferritin mediated by polyphosphate compounds. 627 Dec 55

Bovine bone morphogenetic protein (bBMP) induces differentiation of mesenchymal-type cells into cartilage and bone. bBMP has an apparent Mr of 18,500 +/- 500 and represents less than 0.001% of the wet weight of bone tissue. A Mr 34,000 protein resembling osteonectin is separated by extraction with Triton X-100. A Mr 24,000 protein and about half of a Mr 22,000 protein are disassociated from bBMP by precipitation in 1.5 M guanidine hydrochloride. Aggregates of bBMP and a Mr 14,000 protein are insoluble in aqueous media; the bBMP becomes soluble when the Mr 14,000 protein is disassociated in 6 M urea and removed from the solution by ultrafiltration. Three separate molecular species with apparent Mrs 18,500, 17,500, and 17,000 are eluted at 0.10, 0.15, and 0.20 M phosphate ion concentrations, respectively, from a hydroxy-apatite column. The Mr 18,500 protein has the amino acid composition of acidic polylpeptide and includes four half-cystine residues; the pI is 4.9-5.1. The Mr 22,000 component is a chromoprotein resembling ferritin. The NH2-terminal amino acid sequence of the Mr 17,500 protein simulates histone H2B. The Mr 17,000 protein may possess calmodulin activity. Aggregates of the Mr 18,500 and other proteins induce formation of large deposits of bone; the Mr 18,500 protein alone is rapidly absorbed and induces formation of small deposits. None of the other proteins induces bone formation.
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PMID:Purification of bovine bone morphogenetic protein by hydroxyapatite chromatography. 632 Jan 84

Evidence for transient localization of newly synthesized lipopolysaccharide at the periplasmic face of the inner membrane has been obtained by immunoelectron microscopic techniques. Salmonella typhimurium galE mutants in which O-antigen synthesis is dependent on addition of exogenous galactose were employed, and the distribution and fate of pulse-synthesized O antigen was examined by indirect ferritin labeling with anti-O-antigen IgG of spheroplasts prepared by treatment with lysozyme/EDTA. O-reactive lipopolysaccharide appeared rapidly at the exposed periplasmic face of the inner membrane after addition of galactose and was rapidly depleted upon termination of the pulse. Control experiments showed that secondary redistribution of lipopolysaccharide from outer membrane did not occur under the conditions employed for spheroplast formation and immunolabeling, and the pulse-chase kinetics were consistent with those expected for an intermediate in translocation of lipopolysaccharide to the outer membrane. In addition, undecaprenol-linked O antigen was detectable at the periplasmic face of the inner membrane within 30 sec after addition of galactose to a galE deep rough double mutant, and it accumulated stably in that location. The mutation in synthesis of the lipopolysaccharide core in the deep rough strain prevents transfer of O-antigen chains from undecaprenol phosphate to lipopolysaccharide. The result suggests that attachment of O antigen to lipopolysaccharide occurs on the extracytoplasmic side of the inner membrane and supports the conclusion that lipopolysaccharide is translocated to the outer membrane from the periplasmic, rather than the cytoplasmic, face of the inner membrane.
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PMID:An intermediate step in translocation of lipopolysaccharide to the outer membrane of Salmonella typhimurium. 633 98

Haemosiderin was isolated from thalassaemic human spleens by centrifugation through concentrated KI solutions. A method for solubilizing haemosiderin was developed which leaves the iron oxyhydroxide cores and constituent polypeptides intact, facilitating further purification and analysis. Purified haemosiderin contained no detectable haem, trace amounts of carbohydrate, and iron and phosphorus in a molar ration of 6:1; much of the phosphate may be present as core-adsorbed. Several lipids were present, but it is not certain whether these are contaminants or components of the haemosiderin granules. In all preparations examined, a characteristic group of six to seven peptides of apparent Mr 12 900-17 800 were found, with a major band at Mr 14 500 and, in addition, a minor component of Mr 42 000; these peptides co-chromatographed with the cores. Negatively stained electron micrographs suggest that these peptides form an incomplete shell about the cores, consistent with the view that haemosiderin is a proteolytic product of ferritin.
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PMID:Biochemical studies on the isolation and characterization of human spleen haemosiderin. 649 44

The distribution of the surface charge on the cells which constitute the air-blood barrier was investigated by perfusing cationized ferritin (CF) into the vasculature or into the airways of the mouse lung. Binding of CF is selective and defines highly differentiated domains. The most salient finding is that the air-blood barrier proper that includes type I epithelial cell and part of the corresponding avesicular area of the endothelial cell has very few or lacks anionic sites. In the vesicular area of endothelial cells the plasma membrane binds CF homogenously, with the exception of the membrane of plasmalemmal vesicles and transendothelial channels and their associated diaphragms. In contradistinction to the luminal surface of the type I epithelial cell, which is virtually devoid of anionic sites, CF decorates heavily the luminal surface of type II epithelial cells, up to the level of the junction with type I epithelial cells. Extruded lamellar bodies and tubular myelin also binds CF, presumably due to the phosphate groups of the dipalmitoyl phosphatidylcholine. The cell surface of the alveolar macrophages has relatively few binding sites for CF, but significant internalization of the latter occurs at early time intervals. The preferential distribution of anionic sites on cell surfaces of the alveolar-capillary unit may be influential in the transport of molecules and gases across various regions of the air-blood barrier.
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PMID:Differentiated distribution of the cell surface charge on the alveolar-capillary unit. Characteristic paucity of anionic sites on the air-blood barrier. 683 1

Partial characterization of carboxyl, sulfate, and phosphate groups on the Caenorhabditis elegans cuticle and intestinal microvilli was achieved by en face labeling of floating cryosections at two pH levels and specific blockage of sulfate groups by Alcian blue. All negatively charged groups on the cuticle and intestinal microvilli labeled heavily at pH 7.2-7.4. Pretreatment to block sulfate groups followed by ferritin labeling at pH 7.2-7.4 gave a 35% reduction of binding on the cuticle and an 80% reduction in binding on the microvilli. At pH 1.8 or 2.5, only the sulfate groups labeled as shown by the complete abolition of labeling on the cuticle and the microvilli following blockage of the sulfate groups. Molecules with accessible sulfate groups were distributed in clusters throughout the cortical layer of the cuticle, were present in the struts of the median layer but were absent from the basal layer. The advantages of applying molecular probes to cryosections as compared to sections prepared by standard electron microscopical techniques are discussed.
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PMID:Caenorhabditis elegans: characters of negatively charged groups on the cuticle and intestine. 685 68

Energy-dispersive X-ray analysis has been performed on marrow sideroblasts obtained from 10 patients with sideroblastic anaemias or erythroleukaemia (six primary refractory sideroblastic anaemia, two pyridoxine-responsive, one secondary sideroblastic anaemia, two erythroleukaemia). Irrespective of the nature of the disorder associated with the presence of sideroblasts, X-ray analysis of siderotic mitochondria consistently revealed the presence of iron and phosphorus with the average Fe/P intensity ratio measuring 1.4-1.5. Other elements variably detected within siderotic mitochondria included calcium, lead, potassium and zinc. Variation in the presence of these latter elements was detected not only between different patients, but also within different samples taken at different times from a single patient and even among different cells of the same sample. Despite the detection of lead in siderotic mitochondria of a significant number of patients (five out of seven), there was no clinical evidence of lead toxicity. The elemental composition of the intramitochondrial deposits in sideroblasts was distinct from that of ferritin or haemosiderin and probably consists of ferric phosphate, possibly, ferric orthophosphate (FePO4).
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PMID:Energy-dispersive X-ray analysis of the mitochondria of sideroblastic anaemia. 693 57

Iron, copper, and zinc utilization were examined in nine adult males fed a moderate calcium-moderate phosphorus diet (MCaMP), a moderate calcium-high phosphorus diet (MCaHP), and a high calcium-high phosphorus diet (HCaHP) during a 39-day balance study. The moderate and high calcium diets contained 780 mg and 2382 mg calcium daily, respectively. The moderate and high phosphorus diets contained 843 and 2442 mg phosphorus daily, respectively. The calcium supplements were fed as calcium gluconate, while the phosphorus supplements were fed as glycerol phosphate. Subjects lost more iron and copper in their feces and apparently retained less iron and copper when fed the HCaHP diet than when fed the other two diets, but these effects were not statistically significant. Urinary iron and copper excretion were significantly affected by the dietary treatments. Dietary treatments had no effect on subjects' fecal and urinary losses of zinc nor on their apparent retention of zinc. Plasma iron, zinc, copper, and transferrin levels and serum ferritin levels were not affected by the dietary treatments.
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PMID:Effect of dietary calcium and phosphorus levels on the utilization of iron, copper, and zinc by adult males. 705 62

Lectins conjugated with either peroxidase or ferritin were used to detect specific monosaccharide residues on the luminal front of he fenestrated endothelium in the capillaries of murine pancreas and intestinal mucosa. The lectins tested recognize, if accessible, the following residues: alpha-N-acetylgalactosaminyl (soybean lectin), beta-D-galactosyl (peanut agglutinin [PA] and Ricinus communis agglutinin-120 [RCA]), beta-N-acetylglucosaminyl and sialyl residues (wheat germ agglutinin [WGA]), alpha-L-fucosyl (lotus tetragonolobus lectin), and alpha-D-glucosyl and beta-D-mannosyl (concanavalin A [ConA]). Thi labeled lectins were introduced by perfusion in situ after thoroughly flushing with phosphate-buffered saline the microvascular beds under investigation. Specimens were fixed by perfusion, and subsequently processed for peroxidase detection and electron microscopy. Control experiments included perfusion with: (a) unlabeled lectin before lectin conjugate; (b) labeled lectin together with the cognate hapten sugar, and (c) horseradish peroxidase or ferritin alone. Binding sites were found to be relatively homogeneously distributed on the plasmalemma proper, except for Lotus tetragonolobus lectin and Con A, which frequently bound in patches. Plasmalemmal vesicles, transendothelial channels, and their associated diaphragms were particularly rich in residues recognized by RCA and PA (beta-D-galactosyl residues) and by WGA (beta-N-acetylglucosaminyl residues). Receptors for all lectins tested appeared to be absent or considerably less concentrated on fenestral diaphragms. The results reported here extend and complement previous findings on the existence of microdomains generated by the preferential distribution of chemically different anionic sites (Simionescu et al., 1981, J. Cell Biol., 9:605-613 and 614-621).
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PMID:Differentiated microdomains on the luminal surface of capillary endothelium: distribution of lectin receptors. 710 6

Endocrine abnormalities in patients with chronic renal failure are well documented. The present study aimed to assess the influence of long-term erythropoietin (EPO) therapy on endocrine abnormalities in hemodialyzed patients. Two groups of hemodialyzed patients, each of which comprised 17 subjects, were examined. The first group was treated by EPO (EPO group) while the second one did not receive this hormone (No-EPO group). A complete biochemical and hormonal check-up was performed before and at the 3, 6, 9, and 12 month points of the study period. Normal values for the estimated parameters were obtained in appropriately selected sex- and age-matched healthy subjects. After EPO therapy, an increase of the hematocrit value from 21.8 +/- 0.9 to 32.6 +/- 0.9% was observed, which was accompanied by a significant decline of plasma ferritin and saturation of transferrin. In patients of the No-EPO group, a significant although less marked rise of the hematocrit value (21.4 +/- 0.4 to 24.2 +/- 0.6%) was also noticed. EPO therapy did not change plasma levels of electrolytes (Na, K, Ca, inorganic phosphate), osteocalcin, creatinine, glucose, and alkaline phosphatase as well as plasma concentrations of calcium-related hormones (PTH, calcitonin, 1,25[OH]2D3), vasopressin, and triiodothyronine. EPO treatment induced a significant decrease in somatotropin, prolactin, follitropin, lutropin, ACTH, cortisol, plasma renin activity, aldosterone, noradrenaline, adrenaline, dopamine, glucagon, pancreatic polypeptide, and gastrin plasma levels and an increase in plasma insulin, estradiol, testosterone, atrial natriuretic peptide, thyrotropin, and thyroxine.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Function of endocrine organs in hemodialyzed patients of long-term erythropoietin therapy. 762 22


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