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Mouse transcobalamin has features resembling both human transcobalamin and haptocorrin.

Hygum K, Lildballe DL, Greibe EH, Morkbak AL, Poulsen SS, Sorensen BS, Petersen TE, Nexo E - PLoS ONE (2011)

Bottom Line: Subsequent sequencing identified the protein as TC.Analysis of the TC-mRNA level showed a high TC transcript level in these glands and also in the kidney.Our results suggest that the Cbl-binding proteins present in the circulation and exocrine glands may vary amongst species.

View Article: PubMed Central - PubMed

Affiliation: Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark.

ABSTRACT
In humans, the cobalamin (Cbl) -binding protein transcobalamin (TC) transports Cbl from the intestine and into all the cells of the body, whereas the glycoprotein haptocorrin (HC), which is present in both blood and exocrine secretions, is able to bind also corrinoids other than Cbl. The aim of this study is to explore the expression of the Cbl-binding protein HC as well as TC in mice. BLAST analysis showed no homologous gene coding for HC in mice. Submaxillary glands and serum displayed one protein capable of binding Cbl. This Cbl-binding protein was purified from 300 submaxillary glands by affinity chromatography. Subsequent sequencing identified the protein as TC. Further characterization in terms of glycosylation status and binding specificity to the Cbl-analogue cobinamide revealed that mouse TC does not bind Concanavalin A sepharose (like human TC), but is capable of binding cobinamide (like human HC). Antibodies raised against mouse TC identified the protein in secretory cells of the submaxillary gland and in the ducts of the mammary gland, i.e. at locations where HC is also found in humans. Analysis of the TC-mRNA level showed a high TC transcript level in these glands and also in the kidney. By precipitation to insolubilised antibodies against mouse TC, we also showed that >97% of the Cbl-binding capacity and >98% of the Cbl were precipitated in serum. This indicates that TC is the only Cbl-binding protein in the mouse circulation. Our data show that TC but not HC is present in the mouse. Mouse TC is observed in tissues where humans express TC and/or HC. Mouse TC has features in common with both human TC and HC. Our results suggest that the Cbl-binding proteins present in the circulation and exocrine glands may vary amongst species.

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Immunohistochemical localization of TC in mouse tissues using anti-mouse TC.(A, B) The submaxillary gland shows positive staining in the granules of the granular, convoluted tubule cells. (C, D, E) Lactating mammary gland with some reaction in the luminal secretion. Magnifications: (A, C) X 75, (B) X 300, (D, E) X 475.
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pone-0020638-g004: Immunohistochemical localization of TC in mouse tissues using anti-mouse TC.(A, B) The submaxillary gland shows positive staining in the granules of the granular, convoluted tubule cells. (C, D, E) Lactating mammary gland with some reaction in the luminal secretion. Magnifications: (A, C) X 75, (B) X 300, (D, E) X 475.

Mentions: The TC expression in mice was examined by immunohistochemistry, Figure 4. TC was found in the granules of the granular, convoluted tubule cells in the submaxillary glands and in the luminal secretion in the lactating mammary glands.


Mouse transcobalamin has features resembling both human transcobalamin and haptocorrin.

Hygum K, Lildballe DL, Greibe EH, Morkbak AL, Poulsen SS, Sorensen BS, Petersen TE, Nexo E - PLoS ONE (2011)

Immunohistochemical localization of TC in mouse tissues using anti-mouse TC.(A, B) The submaxillary gland shows positive staining in the granules of the granular, convoluted tubule cells. (C, D, E) Lactating mammary gland with some reaction in the luminal secretion. Magnifications: (A, C) X 75, (B) X 300, (D, E) X 475.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3105116&req=5

pone-0020638-g004: Immunohistochemical localization of TC in mouse tissues using anti-mouse TC.(A, B) The submaxillary gland shows positive staining in the granules of the granular, convoluted tubule cells. (C, D, E) Lactating mammary gland with some reaction in the luminal secretion. Magnifications: (A, C) X 75, (B) X 300, (D, E) X 475.
Mentions: The TC expression in mice was examined by immunohistochemistry, Figure 4. TC was found in the granules of the granular, convoluted tubule cells in the submaxillary glands and in the luminal secretion in the lactating mammary glands.

Bottom Line: Subsequent sequencing identified the protein as TC.Analysis of the TC-mRNA level showed a high TC transcript level in these glands and also in the kidney.Our results suggest that the Cbl-binding proteins present in the circulation and exocrine glands may vary amongst species.

View Article: PubMed Central - PubMed

Affiliation: Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark.

ABSTRACT
In humans, the cobalamin (Cbl) -binding protein transcobalamin (TC) transports Cbl from the intestine and into all the cells of the body, whereas the glycoprotein haptocorrin (HC), which is present in both blood and exocrine secretions, is able to bind also corrinoids other than Cbl. The aim of this study is to explore the expression of the Cbl-binding protein HC as well as TC in mice. BLAST analysis showed no homologous gene coding for HC in mice. Submaxillary glands and serum displayed one protein capable of binding Cbl. This Cbl-binding protein was purified from 300 submaxillary glands by affinity chromatography. Subsequent sequencing identified the protein as TC. Further characterization in terms of glycosylation status and binding specificity to the Cbl-analogue cobinamide revealed that mouse TC does not bind Concanavalin A sepharose (like human TC), but is capable of binding cobinamide (like human HC). Antibodies raised against mouse TC identified the protein in secretory cells of the submaxillary gland and in the ducts of the mammary gland, i.e. at locations where HC is also found in humans. Analysis of the TC-mRNA level showed a high TC transcript level in these glands and also in the kidney. By precipitation to insolubilised antibodies against mouse TC, we also showed that >97% of the Cbl-binding capacity and >98% of the Cbl were precipitated in serum. This indicates that TC is the only Cbl-binding protein in the mouse circulation. Our data show that TC but not HC is present in the mouse. Mouse TC is observed in tissues where humans express TC and/or HC. Mouse TC has features in common with both human TC and HC. Our results suggest that the Cbl-binding proteins present in the circulation and exocrine glands may vary amongst species.

Show MeSH