Human transferrin: cDNA characterization and chromosomal localization.

Abstract

Transferrin (Tf) is the major iron binding protein in vertebrate serum. It shares homologous amino acid sequences with four other proteins: lactotransferrin, ovotransferrin, melanoma antigen p97, and HuBlym-l. Antigen p97 and the Tf receptor genes have been mapped on human chromosome 3. The goal of the study described here was to initiate the characterization of the Tf gene by identifying and characterizing its cDNA and mapping its chromosomal location. Recombinant plasmids containing human cDNA encoding Tf have been isolated by screening an adult human liver library with a mixed oligonucleotide probe. Within the 2.3 kilobase pairs of TfcDNA analyzed, there is a probable leader sequence encoded by 57 nucleotides followed by 2037 nucleotides that encode the homologous amino and carboxyl domains. During evolution, three areas of the homologous amino and carboxyl domains have been strongly conserved, possibly reflecting functional constraints associated with iron binding. Chromosomal mapping by in situ hybridization and somatic cell hybrid analysis indicate that the Tfgene is located at q21-25 on human chromosome 3, consistent with linkage of the Tf, Tf receptor, and melanoma p97 loci.Transferrin (Tf) carries ferric iron from the intestine, reticuloendothelial system, and liver parenchymal cells to all proliferating cells in the body. The family of Tf-like proteins represents the product of an intragenic duplication followed by a series of independent gene duplications (1-4). Serum Tf (1), hen ovotransferrin (2, 3), lactotransferrin (4), melanoma antigen p97 (5), and a transforming protein from chicken lymphoma ChBlym-1 (6) share strong amino acid sequence homologies. A transforming protein from Burkitt lymphomas recently described (7) may also belong to the Tf family. There is also significant internal homology in the amino-terminal (NH2) and carboxyl-terminal (COOH) domains of Tf, lactotransferrin, and ovotransferrin (1-4). For example, the NH2 and COOH domains of human Tf reveal 40% identity when the NH2 domain (residues 1-336) and the COOH domain (residues 337-678) are compared (1). In the study described Screening of cDNA Clones. The cDNA library, kindly provided by Stuart H. Orkin (Harvard Medical School, Boston) was constructed from human liver RNA as described (10). The cDNA library was incubated overnight on L agar plates containing 10 jig of tetracycline per ml and was transferred to nitrocellulose filters. The plasmids were amplified with 250 ,tg of chloramphenicol per ml and the filters were prepared for hybridization as described by Grunstein and Hogness (11). The filters were hybridized at 37°C with 32P-labeled oligonucleotide mixed probes as described by Wallace, et al. (12). The hybridization mixture contained 0.9 M NaCl, 0.09 M Tris HCl (pH 7.5), 0.006 M EDTA, 0.5% NaDodSO4, Denhardt's (13) solution (5 x strength), 100 ,ug of denatured Escherichia coli DNA per ml, and 6.4 ng of 5' end-labeled oligonucleotide mixed probes per ml having a specific activity of -7 x 108 cpm/,ug.Preparation...

Two genetically defined trans-acting loci coordinately regulate overlapping sets of liver-specific genes

“…pmcGRH1 (S. R.. unpublished data) contains the 1 kb Hindlll fragment of the mouse glucocortlcoid receptor cDNA clone (position +1319 to +2347) from pSV2Wrec (Danielsen et al, 1986). pmTF-1 (1.5 kb EcoRl fragment) and pmTF-2 (750 bp EcoRl fragment) are subclones of the full-length mouse transferrin cDNA (S. R.. unpublished data), which have been identified by revealing more than 86% sequence homology to the human transferrin gene (Yang et al, 1984). pmcCREB61 (S. R., unpublished data) contains a 1.2 kb EcoRl fragment corresponding to the mouse cDNA encoding the CREB isolated by cross-hybridization with the human CREB cDNA clone (Hoeffler et al, 1988).…”

Anomalous Venous Blood Flow and Iron Deposition in Multiple Sclerosis

“…Neurons are highly polarized, and proteins of neuronal homeostasis and CNS physiology are synthesized in cell bodies and then transported to functional sites at synapses. In cooperation with iron regulatory proteins, ferritin, and ferroportin, transferrin maintains the iron requirement under control across neuron transport in the CNS by regulating iron absorption, transport, storage, and utilization by brain cells (Rouault, 2001;Yang et al, 1984;Chua et al, 2007).…”

Autocrine growth induced by transferrin-like substance in bladder carcinoma cells

“…The N-terminal sequence up to the 17th amino acid residue was determined to be S-A-G-W-N-I-P-I-G-L-L-Y-X-D-L-P-E-, in which X seemed to be C (Cys). As a result of an investigation of the homology using the protein database, this sequence was found to be completely identical to the sequence of amino acid residues 125-141 from the N-terminus of human transferrin (MacGillivray et al, 1982;Yang et al;.…”