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Date: 30-11-2021
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Glycoprotein Overview
Glycoproteins are proteins to which oligosaccharides (glycans) are covalently attached. [Note: Glycosylation is the most common posttranslational modification of proteins.] They differ from the proteoglycans in several important ways. Glycoproteins contain highly variable amounts of carbohydrate but typically less than that of proteoglycans. For example, the glycoprotein immunoglobulin G (IgG) contains <4% of its mass as carbohydrate, whereas the proteoglycan aggrecan contains >80%.
In glycoproteins, the glycan is relatively short (usually two to ten sugar residues in length, although it can be longer); does not contain repeating disaccharide units and, consequently, is structurally diverse; is often branched instead of linear; and may or may not be negatively charged. Membrane-bound glycoproteins participate in a broad range of cellular phenomena, including cell-surface recognition (by other cells, hormones, and viruses), cell-surface antigenicity (such as the blood group antigens), and as components of the ECM and of the mucins of the gastrointestinal and urogenital tracts, where they act as protective biologic lubricants. In addition, almost all of the globular proteins present in human plasma are glycoproteins, although albumin is an exception. Figure 1summarizes some glycoprotein functions.
Figure 1: Functions of glycoproteins.
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مخاطر عدم علاج ارتفاع ضغط الدم
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اختراق جديد في علاج سرطان البروستات العدواني
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نشر مظاهر الفرح في مرقد أبي الفضل العباس بذكرى ولادة السيدة زينب (عليهما السلام)
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