Ferritin complex

Fleming J, Joshi JG. 1987. Ferritin Isolation of aluminum-ferritin complex from brain. Proc Natl Acad Sci U S A 84 7866-7870. 

In serum, absorbed vanadium is transported mainly bound to transferrin (Lager-kvist etal. 1986, Kustin and Robinson 1995). Vanadium in rat milk was found mainly in the protein fraction, and perhaps also in lactoferrin (Sabbioni and Rade 1980), in which form it is transferred from the mother to the pups. In older rats, vanadium appears to be converted into vanadyl-transferrin and ferritin complexes in the plasma and body fluids (Edel and Sabbioni 1989, Sabbioni and Marafante 1981). 

Iron can be drawn from ferritin stores, transported in the blood as transferrin, and taken up via receptor-mediated endocytosis by cells that require iron (e.g., by reticulocytes that are synthesizing hemoglobin). When excess iron is absorbed from the diet, it is stored as hemosiderin, a form of ferritin complexed with additional iron that cannot be readily mobilized. 

Two glycoproteins (mol. wt. 1.8 x 10 and 3.4 x 10 ) have been identified in both the nuclei and nuclear membranes of rat liver. These glycoproteins, which bind in concanavalin A-ferritin complexes, are located exclusively on the cisternal surface of the membranes. Rough- and smooth-microsomal fractions and Golgi membranes of rat liver have been shown to contain different types and amounts of polyprenyl phosphates and exhibit specificity as sugar acceptors from sugar nucleotides. ... 

FIGURE 7.17 Separation of a complex mixture on Fractogel EMD BioSEC (S) with a column dimension of 1000 X 50 mm (Superformance glass column). The sample contained ferritin (I), immunoglobulin G (2), transferrin (3), ovalbumin (4), myoglobin (5), aprotinin (6), and vitamin B, (7). Five milliliters of the mixture was injected onto the column at a flow rate of 3 ml/min (eluent 20 mAI sodium phosphate buffer, 0.1 M NaCI, pH 7.2). 

Serum ferritin Less than 1 0-20 mcg/L (22-44 pmol/L) Ferritin is the protein-iron complex found in macrophages used for iron storage low in iron-deficiency anemia. 

Serum ferritin A complex protein formed in the intestine, containing about 23% iron, the amount of ferritin found in serum is directly related to iron storage in the body. 

The core of the iron storage protein ferritin consists of a hydrated ferric oxide-phosphate complex. Various models have been proposed which feature Fe111 06 oct., Fe111 O4 tet. or Fe111 O4 tet. Fe111 06 oct. complexing the first listed is preferred by Gray (99) on the basis of the electronic absorption spectrum. The protein very closely related to ferritin which occurs in the mold Phycomyces blakesleeanus contains... 

Figure 7.5 Model of ferritin (and erythroid a-aminolaevulinate synthase) translation/ribosome binding regulation by IRP. In (a), with IRP not bound to the IRE (1) binding of the 43S preinitiation complex (consisting of the small ribosomal 40S subunit, GTP and Met-tRNAMet) to the mRNA is assisted by initiation factors associated with this complex, as well as additional eukaryotic initiation factors (elFs) that interact with the mRNA to facilitate 43S association. Subsequently (2), the 43S preinitiation complex moves along the 5 -UTR towards the AUG initiator codon, (3) GTP is hydrolysed, initiation factors are released and assembly of the 80S ribosome occurs. Protein synthesis from the open reading frame (ORF) can now proceed. In (b) With IRP bound to the IRE, access of the 43S preinitiation complex to the mRNA is sterically blocked. From Gray and Hentze, 1994, by permission of Oxford University Press.

Traditional methods for fabricating nano-scaled arrays are usually based on lithographic techniques. Alternative new approaches rely on the use of self-organizing templates. Due to their intrinsic ability to adopt complex and flexible conformations, proteins have been used to control the size and shape, and also to form ordered two-dimensional arrays of nanopartides. The following examples focus on the use of helical protein templates, such as gelatin and collagen, and protein cages such as ferritin-based molecules. 

The formation of nitric oxide in microsomes results in the inhibition of microsomal reductase activity. It has been found that the inhibitory effect of nitric oxide mainly depend on the interaction with cytochrome P-450. NO reversibly reacts with P-450 isoforms to form the P-450-NO complex, but at the same time it irreversibly inactivates the cytochrome P-450 via the modification of its thiol residues [64]. Incubation of microsomes with nitric oxide causes the inhibition of 20-HETE formation from arachidonic acid [65], the generation of reactive oxygen species [66], and the release of catalytically active iron from ferritin [67],... 

The answer is b. (Hardman, pp 1324,1668. KatzmigT p 1009J Deferoxamine is the treatment of choice in acute Fe overload when the plasma concentration of Fe exceeds the total Fe binding capacity It has a high affinity for loosely bound Fe in Fe-carrying proteins such as ferritin, hemosiderin, and transferrin. The metal complex is excreted in the urine. 

Forming a metal complex may serve to activate NO toward either nucleophilic or electrophilic attack depending on the nature of the metal complex and its oxidation state. Of particular interest biologically are the reactions with nucleophiles since this may well be a mechanism for thionitrosyl formation (e.g. Eq. (55)) as well as for reductively labiliz-ing metals in insoluble matrices like ferritin. 

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