Glycoproteins respiratory mucus

Van Halbeek H, Breg J, Vliegenthart JE, Klein A, Lamblin G, Roussel P. Isolation and structural characterization of low-molecular-mass monosialyl oligosaccharides derived from respiratory-mucus glycoproteins of a patient suffering from bronchiectasis. Eur. J. Biochem. 1988 177(2) 443 60. 

Respiratory mucus is a complex mixture of glycoproteins, proteoglycans, lipids, and smaller quantities of other proteins (82). Glycoproteins appear to be the most important component conferring viscoelastic properties to the mucus (see also Chap. 13). 

The initial step in the viral life cycle is the attachment of virus particles to the cell surface. Attachment is mediated by binding of the virus to a receptor. Sometimes co-receptors are also involved that might promote post-attachment events in the entry process. Receptor molecules are crmstituents of the cell membrane, and the receptor determinant, the stmcture to which the virus binds, may be either a protein epitope or the carbohydrate of a glycoprotein or a glycolipid. Soluble proteins present in body fluids and in mucus oti respiratory and enteric epithelia may also contain such carbohydrates and therefore interfere with virus binding to the cell siuface. 

Glycoproteins are slimy and gelatinous substances in the synovial fluids of joints, liquids of eye sockets and in various secretions, such as respiratory tract mucus. They also occur in saliva, egg white and other viscous materials. 

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