Glycoproteins secretion

Vitamin Bj2 is absorbed bound to intrinsic factor, a small glycoprotein secreted by the parietal cells of the... 

Bi2 are only about 2 meg, it would take about 5 years for all of the stored vitamin B12 to be exhausted and for megaloblastic anemia to develop if Bi2 absorption were stopped. Vitamin B12 in physiologic amounts is absorbed only after it complexes with intrinsic factor, a glycoprotein secreted by the parietal cells of the gastric mucosa. Intrinsic factor combines with the vitamin Bi2 that is liberated from dietary sources in the stomach and duodenum, and the intrinsic factor-vitamin Bi2 complex is subsequently absorbed in the distal ileum by a highly selective receptor-mediated transport system. Vitamin Bi2 deficiency in humans most often results from malabsorption of vitamin B12 due either to lack of intrinsic factor or to loss or malfunction of the specific absorptive mechanism in the distal ileum. Nutritional deficiency is rare but may be seen in strict vegetarians after many years without meat, eggs, or dairy products. 

Gawlitzek M, Valley U, Wagner R (1998), Ammonium ion and glucosamine dependent increases of oligosaccharide complexity in recombinant glycoproteins secreted from cultivated BHK-21 cells, Biotechnol. Bioeng. 57 518-528. 

P2Y2 receptors are present in the epithelial cells of the ocular surface and stimulation of them by ATP increases mucin-like glycoprotein secretions in conjunctival... 

N-acetylneuraminic acid protects the Intrinsic factor , a neuraminic add glycoprotein secreted by the mucous membrane of the stomach, against the action of proteol) c enzymes. The intrinsic factor binds vitamin B12 ingested with the food and allows its absorption in the lower sections of the intestine. The intrinsic factor still retains its ability to bind vitamin Bn after removal of the neuraminic acid, but the absorption of the vitamin from the intestinal lumen is no longer possible. 

Pos, O., Van Dijk, W., Ladiges, N., Linthorst, C., Sala, M., van Tiel, D. and Boers, W. (1988) Glycosylation of four acute-phase glycoproteins secreted by rat liver cells in vivo and in vitro. Effects of inflammation and dexamethasone. European Journal of Cell Biology, 46,121-128. 

Vitamin Bn can be deficient due to a lack of intrinsic factor, which is a glycoprotein secreted by gastric parietal cells. A lack of intrinsic factor or a dietary deficiency of cobalamin can cause pernicious anemia and neuropsychiatric symptoms. The only known treatment lor intrinsic factor deficiency (vitamin Bn deficiency) is intramuscular injection of cyanocobalamin throughout the patient s life. 

Figure 42-2. Absorption, transport and storage of vitamin Bj. IF = intrinsic factor, a glycoprotein secreted by gastric parietal cells TC = transcobalamins, blood proteins that carry cobalamin to the Uver. (Reproduced, with permission, from D.B. Marks, et al. Basic Medical Biochemistry A Clinical Approach. Philadelphia Lippincott Williams Wilkins, 1996 619.)...

Thyroglobulin (TG). This glycoprotein secreted by thyroid follicular cells is a major autoantigen in autoimmune thyroid diseases. Thyroglobulin autoantibodies were found in patients with autoimmune thyroiditis ( - thyroiditis, autoimmune) and Graves disease. 

Bird, A. F. (1990) Vital staining of glycoprotein secreted by infective third stage larvae of Haemonchus contortus prior to exsheathing. Int. J. Parasitol. 20 619-623. 

Vitamin (extriasic factor) is absorbed only when complexed with iiarinsu-- Ji c r r. a glycoprotein secreted by the parietal eellx of the gastric mucosa. Absorption occurs in the distal ileum by a highly... 

Interferons (IFN), cytokines that display antiproliferative, antitumor, antiviral, and immunomodulatory properties. They regulate somatic cell growth, division, and apoptosis. The biological effects of IFNs are primarily mediated via activation of the JAK/STAT pathway. IFN are glycoproteins secreted by virus-infected vertebrate cells preventing viral proliferation, largely by inhibition of protein synthesis in other infected cells. Three families of IFN have been characterized (a) IFN-a or leukocyte... 

Glycoproteins in the sputum of patients with chronic bronchitis have been solubilized and then fractionated on Sepharose 4B into components of high and low molecular weight The sputum of bronchial patients contains more components of low molecular weight. Mucins from macroscopically healthy areas of the bronchial mucosa of six adults are anionic and contain residues of sialic acid and sulphate. Affinity chromatography on immobilized Ricinus communis lectin has enabled the mucins and other glycoproteins secreted by human bronchia to be characterized. ... 

Vitamin B12 deficiency results more commonly from a stomach defect than from a dietary deficiency. Before it can be absorbed the vitamin B12 (extrinsic factor) that is released from associated peptides and proteins in the stomach must combine with the intrinsic factor, a small glycoprotein secreted by the parietal cells. Subjects who suffer from pernicious anaemia fail to produce intrinsic factor with the result that the vitamin is not absorbed and must be given by injection. Vitamin B]2 produced by microbes in the lower reaches of the intestine is of no use to the body. 

Efficient absorption of cobalamin requires that the vitamin form a macromolecular complex with the glycoprotein secreted by the stomach. In patients with pancreatic insufficiency, cobalamin absorption is poor, suggesting that pancreatic proteases are necessary for this process, although the mechanism responsible has not yet been identified. For efficient absorption, the distal small bowel must be intact, and in its absence, the absorption of cobalamin is... 

This binding protein is intrinsic factor , so called because in the early studies of pernicious anaemia (section 11.10.3) it was found that two curative factors were involved — an extrinsic or dietary factor, which we now know to be vitamin B d an intrinsic or endogenously produced factor. Intrinsic factor is a small glycoprotein secreted by the parietal cells of the gastric mucosa, which also secrete hydrochloric acid. 

Intrinsic factor is required for the absorption of vitamin B12. This is a glycoprotein secreted by the mucosal cells of the stomach which combines with the vitamin and is then transported into the mucosal cells of the ileum. 

A glycoprotein secreted by the secretory cells of the digestive tract. It functions to (1) facilitate the smooth movement of food through the digestive tract, and (2) provide a protective coating to the gastric and duodenal mucosa against the corrosive action of hydrochloric acid. 

A glycoprotein secreted by spiders onto webs to help catch prey is being considered as a possible biological adhesive for surgery (Choresh et al. 2009). 

H. H. Freeze, D. Wolgast, Structural analysis of N-linked oligosaccharides from glycoproteins secreted by Dictyostelium discoideum. Identification of mannose 6-sulfate. J. Biol Chem. 1986 261, 127-34. 

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