Glycoproteins, content

Meyers MB, Scotto KW, Sirotnak FM. P-glycoprotein content and mediation of vincristine efflux correlation with the level of differentiation in luminal epithelium of mouse small intestine. Cancer Commun 1991 3(5) 159-165. 

Concerning ulcers induced by absolute ethanol, pretreatment with silymarin stimulated mucus secretion, but did not modify the concentration of total proteins and hexosamines [99]. By contrast, in the same experimental model, Reyes et al. [98] found that mucus amount was not modified by the ethylacetate extract of Erica andevalensis, although there was an increase in the concentration of its components. Perez-Guerrero et al. [113] showed that rutin, the glycoside of quercetin, has a protective effect, although it did not induce any changes in the amount of mucus or in its glycoprotein content. 

Water can bind to mucous glycoprotein (MGP) macromolecules and influence viscosity. Viscosity can be increased by dehydration of the mucus, as can adhesion of mucus-epithelium. In purulent sputum, the correlation between viscosity and dry weight of solids is poor and may explain why mucous glycoprotein content is a poor index of viscoelasticity in chronic bronchitis, bronchiectasis, and cystic fibrosis. Mucus s viscoelasticity increases with acidic pH (3), causing reduced mucociliary clearance. Its viscoelasticity is also dependent on the content of low molecular weight electrolytes. These properties reflect the polyelectrolyte nature of mucins (4-6). 

Factor V. High in sialic acid content. Factor V is a large asymmetric single-chain glycoprotein that becomes an active participant in the coagulation cascade when it is converted to its active form by a-thrombin. Approximately 25% of human Factor V is found in the whole blood associated with platelets. Factor V is an essential cofactor along with Factor Xa plus phosphohpid plus Ca " in the conversion of prothrombin to thrombin. 

Glycoproteins occur in most organisms, from bacteria to humans. Many vimses also contain glycoproteins, some of which have been much investigated, in part because they are very suitable for biosynthetic studies. Numerous proteins with diverse functions are glycoproteins (Table 47-1) their carbohydrate content ranges from 1% to over 85% by weight. 

After the virus has attached to CD4 and chemokine receptors, another viral glycoprotein (gp41) assists with viral fusion to the cell and internalization of the viral contents. The viral contents include single-stranded RNA, an RNA-dependent DNA polymerase (also known as reverse transcriptase), and other enzymes. Using the single-stranded viral RNA as a template, reverse transcriptase synthesizes a complementary strand of DNA. The single-stranded viral RNA is removed from the newly formed DNA strand by ribonuclease H, and reverse transcriptase completes the synthesis of double-stranded DNA. The... 

Biological membranes consist of lipids, proteins and also sugars, sometimes mutually bonded in the form of lipoproteins, glycolipids and glycoproteins. They are highly hydrated—water forms up to 25 per cent of the dry weight of the membrane. The content of the various protein and lipid components varies with the type of biological membrane. Thus, in... 

There are several positive factors using BSA in the basolateral medium. First, it mimics the in vivo situation where the circulating blood provides an excellent base for sink conditions due to a large volume and content of serum proteins such as albumin (serum protein content and alpha-glycoproteins) [108]. Second, serum albumin hinders adsorption onto plastic surfaces and filters and thereby stops the... 

The content by weight of carbohydrate in glycoproteins may vary from only a few percent to over 50 percent in some proteins in mucous secretions. Although the function of the polysaccharide in most glycoproteins is unknown, in some cases it may provide hydrophilicity, recognition, and points of noncovalent interaction with other proteins through lectin-like affinity binding. 

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