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)

Evidence is presented that French-bean (Phaseolus vulgaris) seed ferritin is composed of one type of subunit with an apparent Mr of 26500. In normal and iron-loaded leaf tissues it is detected immunologically with an antiserum raised against purified bean seed ferritin and migrates in SDS (sodium dodecyl sulphate)/polyacrylamide-gel electrophoresis with the same mobility as the bean seed ferritin subunit. The biosynthetic pathway of ferritin in normal and iron-loaded leaves was investigated. RNA was extracted, fractionated into polyadenylated RNA and translated in a cell-free rabbit reticulocyte lysate and a wheat-germ-extract system. The products were identified by SDS/polyacrylamide-gel electrophoresis after indirect immunoprecipitation. In all cases the ferritin product had an Mr 5000 higher than that of the native subunit. Uptake and processing of the precursor form of ferritin from iron-loaded leaves by intact chloroplasts was demonstrated. This indicates that, in iron-loaded leaves, ferritin acts as a chloroplast protein. We propose that the ferritin precursor in normal leaves follows the same biosynthetic pathway. This suggests that the iron-buffering function of ferritin in plants takes place in the chloroplast and that non-functional cellular iron will accumulate in this cell organelle.
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PMID:Phytoferritin is synthesized in vitro as a high-molecular-weight precursor. Studies on the synthesis and the uptake in vitro of the precursors of ferritin and ferredoxin by intact chloroplasts. 662 65

A critical analysis of the present erythropoietic pathway reveals two problems which require resolving. One is the paradox of the basophilic erythroblast, and the other is the fate of the extruded red cell nucleus. The problems can be overcome if erythropoiesis is looked at differently, and the orthochromatic normoblast considered to arise directly from a denuded stem cell nucleus as has been previously suggested. The orthochromatic normoblast extrudes its nucleus leaving behind a reticulocyte. The extruded but functionally impaired nucleus of the orthochromatic normoblast then gives rise to a polychromatic normoblast, a defective cell. The poorly made cytoplasm of the polychromatic normoblast is shed and its nucleus, now non-functional, undergoes complete dissolution into an aggregate of ultrafine particles. The theory has the advantage that the fate of the extruded red cell nucleus can be explained without having to introduce phagocytosis by macrophages and all the immunological difficulties which this entails. The new pathway does away with the basophilic erythroblast as a haemoglobin-producing cell, and it is argued that the cell instead is a ferritin storage cell, and that erythropoiesis is the result of two separate but interdependent pathways, a ferritin storage pathway and a haemoglobin production pathway. Evidence is put forward to support the new pathways.
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PMID:The paradox of Ferrata and the fate of the extruded red cell nucleus: two problems concerning erythropoiesis in the human. 766 25

A 34 year old diabetic man with a complete deficiency of serum ferroxidase activity, regardless of the presence of serum ceruloplasmin (Cp), a multicopper ferroxidase protein, is described. The patient had had diabetes mellitus for 13 years, and was also found to have retinal degeneration accompanied by the development of a hearing disturbance of unknown aetiology. Laboratory examination showed markedly increased serum ferritin and low serum iron. Magnetic resonance imaging showed a pronounced hypointensity in the putamen, caudate, cerebellar dentate, and thalamus on T2 weighted images, and also disclosed a low level signal in the liver, suggesting the accumulation of some magnetic substances in the brain and liver. Liver biopsies histochemically identified iron deposition in the hepatocytes. Most of these findings were consistent with the newly established autosomal recessive disease "aceruloplasminaemia", except for the presence of serum Cp and the lack of apparent neurological symptoms. Interestingly, no ferroxidase activity was detected in the patient's serum, whereas suppressed ferroxidase activity was found in his mother's serum. A nucleotide sequence analysis of the Cp gene showed two mutations; a C to T substitution at nucleotide 2701 in exon 16, resulting in a nonsense mutation at amino acid 882 (Arg882ter), and a T to G substitution at nucleotide 2991 in exon 17, resulting in an amino acid alternation at amino acid 978 (His978Gln). The second mutation was also found in the patient's mother. The absence of serum ferroxidase activity despite the presence of serum Cp protein in this compound heterozygote was considered to be due to the production of a non-functional Cp harbouring no ferroxidase activity.
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PMID:A case of aceruloplasminaemia: abnormal serum ceruloplasmin protein without ferroxidase activity. 1190 23

HFE-linked hereditary hemochromatosis is a common form of iron-overload disease in European populations. We studied the role of HFE in macrophage iron metabolism. Patients under venesection treatment had higher EPO levels and drastically reduced levels of transferrin receptor (TfRC and TfR2) mRNA, and also decreased levels of HAMP mRNA in macrophages cultured in autologous serum. Macrophages from C282Y/C282Y patients cultured either in autologous serum or in FBS with or without iron supplementation, had elevated CYBRD1 (cytochrome b reductase 1), SLC40A1 (ferroportin) and FTL (ferritin L) mRNA levels. Those incubated with holo-Tf also showed lower levels of TfRC and TfR2 mRNA. Iron flux from C282Y/C282Y macrophages incubated with a low concentration of non-transferrin-bound iron (NTBI) was similar to that from wild-type macrophages, but incubation with holo-Tf or high NTBI did not trigger a continuous increase in the cytosolic calcein-chelatable iron pool in C282Y/C282Y macrophages conversely to wild-type cells. All culture conditions revealed a high level of intracellular ferritin in C282Y/C282Y macrophages compared to wild-type cells. These results suggest that the non-functional C282Y form of HFE may alter the balance between cytosolic calcein-chelatable iron and sequestered iron, thereby disrupting the iron uptake and release equilibrium in cells involved in iron storage.
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PMID:Iron metabolism in macrophages from HFE hemochromatosis patients. 2067 64