Immunohistochemical Localization of Transferrin in the Pre- and Postnatal Bovine Brain (original) (raw)
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Neurochemical Research, 2008
Transferrin-binding protein (TfBP) has been shown to be a novel protein, structurally related to the chicken heat shock protein 108. The physiological function of this protein, however, has not yet been established. Antiserum to TfBP selectively stains transferrin-and ironrich oligodendrocytes and choroidal epithelium in the adult and embryonic chick brain, suggesting a role for this protein in transferrin and iron storage in these cells. In this study, we further demonstrate TfBP-immunoreactivity (IR) in the blood vessels of the embryonic chick central nervous system. A strong TfBP-IR was present in blood vessels from E6, declined from E10 and was absent by E18. Thus, the expression of the TfBP in the blood vessels precedes its expression in the oligodendrocytes. At the subcellular level, TfBP-IR was confined to the cytoplasm of capillary pericytes while the Tf-receptor IR was associated with the capillary endothelium of the brain. The up-regulated expression of TfBP, together with the Tf-receptor of the brain capillaries, suggests that pericytes may be associated with the high iron uptake required for the metabolic demands of the developing brain.
The cDNA sequence and primary structure of the chicken transferrin receptor
Gene, 1991
Recombinant cDNA clones encoding the chicken transferrin receptor (cTR) have been isolated and sequenced. Comparison of the deduced primary structure of cTR with those of the human transferrin receptor (hTR) and mouse transferrin receptor (mTR) shows that their size, hydropathy profile, location of sites for posttranslational modifications, and domain organization are highly similar. The cytoplasmic domain of cTR contains the motif Tyr-Xaa-Arg-Phe (YXRF) that is the recognition signal for high-efficiency endocytosis of hTR. The cTR has several highly conserved regions within its extracellular domain, including those flanking the putative N-glycosylation sites. Overall, however, the extracellular domain of cTR is only 53 % identical to the extracellular domains of hTR and mTR. The cTR also lacks three of the six Cys residues found in the extracellular domains of the mammalian TRs. These differences can account for functional and structural properties that distinguish cTR and m~m~ian TRs. cTR indicate that they have a similar structure also
Isolation and characterization of a transferrin binding protein from rat plasma
Biochimica et Biophysica Acta (BBA) - General Subjects, 1990
A transferrin binding protein was isolated from normal rat placenta and from iron-deficient rat plasma using a human transferrin affinity column. The yield of the isolated pure protein from iron-deficient rat plasma was about 0.5 pg/mi plasma. The major protein had a molecular mass of 85 kDa and contained carbohydrate. Reduction with mercaptoethanol did not change the molecular mass of the plasma transferrin binding protein whereas the native placental transferrin receptor of 180 kDa was reduced to 90 kDa. The transferrin binding protein reacted with both monocional and polyclonal antibodies raised against rat transferrin receptor, lmmunoblotting of both normal and iron deficient rat plasma showed that the transferrin binding protein had a molecular mass of 85 kDa. In vitro digestion of purified rat placental transferrin receptor and red blood cells with trypsin provided an identical peptide profile, suggesting that the transferrin binding protein in rat plasma is derived from proteolysis of the extracellular portion of the transferrin receptor of erythroid tissues.
Molecular evolution of the transferrin family and associated receptors
Biochimica Et Biophysica Acta-general Subjects
Background: In vertebrates, serum transferrins are essential iron transporters that have bind and release Fe(III) in response to receptor binding and changes in pH. Some family members such as lactoferrin and melanotransferrin can also bind iron while others have lost this ability and have gained other functions, e.g., inhibitor of carbonic anhydrase (mammals), saxiphilin (frogs) and otolith matrix protein 1 (fish). Scope of review: This article provides an overview of the known transferrin family members and their associated receptors and interacting partners. Major conclusions: The number of transferrin genes has proliferated as a result of multiple duplication events, and the resulting paralogs have developed a wide array of new functions. Some homologs in the most primitive metazoan groups resemble both serum and melanotransferrins, but the major yolk proteins show considerable divergence from the rest of the family. Among the transferrin receptors, the lack of TFR2 in birds and reptiles, and the lack of any TFR homologs among the insects draw attention to the differences in iron transport and regulation in those groups. General significance: The transferrin family members are important because of their clinical significance, interesting biochemical properties, and evolutionary history. More work is needed to better understand the functions and evolution of the non-vertebrate family members. This article is part of a Special Issue entitled Molecular Mechanisms of Iron Transport and Disorders.
Proceedings of the National Academy of Sciences, 1981
A radioimmunoassay was developed to directly assay the presence oftransferrin receptors in human tissues. Antisera developed in a goat against purified human placental transferrin binding protein was purified by fractional sodium sulfate precipitation and adsorption against Sepharose-bound transferrin to remove trace anti-transferrin activity. The antisera immunoprecipitates a Mr 94,000 peptide on "'5I-iodinated syncytial trophoblast membranes from placentae. This polypeptide has been identified previously as the transferrin binding protein of the placenta [Wada, H. G., Hass, P. E. & Sussman, H. H. (1979)J. BioL Chem. 254, 12629-12635]. A standard curve using purified 'MIiodinated placental transferrin receptor and various amounts of the purified noniodinated receptor is sensitive from 5 to 900 ng. A reticulocyte-enriched membrane ghost preparation (5% reticulocyte) gives a value of 9.5 jig of receptor per mg of protein. Normal erythrocyte membrane ghosts show binding (0.57 ,.g of receptor per mg of protein) proportional to the amount of reticulocytes normally present in blood (0.5-1.0%). In other tissues in which the transferrin receptor binding has been reported, purified syncytial trophoblastic membranes are found to have 34.5 #g of receptor per mg of protein, and BeWo cells, a choriocarcinoma cell line, are found to have 15.7 Mg of receptor per mg of protein. In contrast, normal breast tissue, which has no demonstrated transferrin binding, contains only 0.18 Mug of receptor per mg of protein by this method.
The distribution of cerebral expression of the transferrin gene is species specific
Journal of Biological Chemistry
Various plasma proteins, for example, transferrin, are synthesized not only in the liver, but also in the brain. The proportion of transferrin mRNA in total RNA from different regions of brains from various mammalian species was studied by Northern blot analysis. Absolute amounts of transferrin mRNA were determined in brain, choroid plexus, and liver from rats, sheep, and pigs by hybridization in solution followed by ribonuclease protection assay. Corrections for differences in yields of RNA were made using internal RNA standards.
Receptor recognition sites reside in both lobes of human serum transferrin
The Biochemical journal, 1997
The binding of iron by transferrin leads to a significant conformational change in each lobe of the protein. Numerous studies have shown that the transferrin receptor discriminates between iron-saturated and iron-free transferrin and that it modulates the release of iron. Given these observations, it seems likely that there is contact between each lobe of transferrin and the receptor. This is the case with chicken transferrin, in which it has been demonstrated unambiguously that both lobes are required for binding and iron donation to occur [Brown-Mason and Woodworth (1984) J. Biol. Chem. 259, 1866-1873]. Further support to this contention is added by the ability of both N- and C-domain-specific monoclonal antibodies to block the binding of a solution containing both lobes [Mason, Brown and Church (1987) J. Biol. Chem. 262, 9011-9015]. In the present study a similar conclusion is reached for the binding of human serum transferrin to the transferrin receptor. With the use of recombin...
Co-migration and internalization of transferrin and its receptor on K562 cells
The Journal of Cell Biology, 1983
The incorporation of iron into human cells involves the binding of diferric transferrin to a specific cell surface receptor. We studied the process of endocytosis in K562, a human erythroid cell line, by using tetramethylrhodamine isothiocyanate-labeled transferrin (TRITC-transferrin) and fluorescein isothiocyanate-labeled Fab fragments of goat antireceptor IgG preparation (FITC-Fab-antitransferrin receptor antibody). Because the antireceptor antibody and transferrin bind to different sites on the transferrin receptor molecule it was possible to simultaneously and independently follow ligand and receptor. At 4 degrees C, the binding of TRITC-transferrin or FITC-Fab antitransferrin receptor antibody exhibited diffuse membrane fluorescence. At 20 degrees C, the binding of TRITC-transferrin was followed by the rapid formation of aggregates. However, the FITC-Fab antitransferrin receptor did not show similar aggregation at 20 degrees C unless transferrin was present. In the presence of ...
Cloning, structural organization and tissue-specific expression of the rabbit transferrin gene
Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression, 1998
We cloned the rabbit transferrin (rTf) cDNA and gene, and quantified the expression of the rTf gene at the RNA level in various organs. The tissue-specific pattern of expression of rTf gene is different to those in other species, with a high expression in mammary gland and kidney. The exon/intron structure of the rTf gene (17 exons/16 introns) is similar to those of transferrins from other species. The sequence of the rTf cDNA already published is corrected and lengthened in the 5P region, and a likely polymorphism is documented.