glycoprotein n : a conjugated protein having a carbohydrate component
Not to be confused with peptidoglycan.
Glycoproteins are proteins that contain oligosaccharide chains (glycans) covalently attached to their polypeptide side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. In proteins that have segments extending extracellularly, the extracellular segments are often glycosylated. Glycoproteins are often important integral membrane proteins, where they play a role in cell-cell interactions.
N-glycosylation and O-glycosylationThere are two types of glycosylation:
MonosaccharidesMonosaccharides commonly found in eukaryotic glycoproteins include:
The sugar group(s) can assist in protein folding or improve proteins' stability.
ExamplesOne example of glycoproteins found in the body is mucins, which are secreted in the mucus of the respiratory and digestive tracts. The sugars attached to mucins give them considerable water-holding capacity and also make them resistant to proteolysis by digestive enzymes.
Glycoproteins are important for white blood cell recognition, especially in mammals. Examples of glycoproteins in the immune system are:
- molecules such as antibodies (immunoglobulins), which interact directly with antigens
- molecules of the major histocompatibility complex (or MHC), which are expressed on the surface of cells and interact with T cells as part of the adaptive immune response.
- components of the zona pellucida, which surrounds the oocyte, and is important for sperm-egg interaction.
- structural glycoproteins, which occur in connective tissue. These help bind together the fibers, cells, and ground substance of connective tissue. They may also help components of the tissue bind to inorganic substances, such as calcium in bone.
HormonesHormones that are glycoproteins include:
AnalysisA variety of methods used in detection, purification, and structural analysis of glycoproteins are
- Structure of Glycoprotein and Carbohydrate Chain - Home Page for Learning Environmental Chemistry
- Biochemistry 5thE 11.3. Carbohydrates Can Be Attached to Proteins to Form Glycoproteins
- Carbohydrate Chemistry and Glycobiology: A Web Tour SPECIAL WEB SUPPLEMENT Science 23 March 2001 Vol 291, Issue 5512, Pages 2263-2502
glycoprotein in Catalan: Glicoproteïna
glycoprotein in Czech: Glykoproteiny
glycoprotein in Danish: Glykoprotein
glycoprotein in German: Glykoprotein
glycoprotein in Spanish: Glicoproteína
glycoprotein in French: Glycoprotéine
glycoprotein in Italian: Glicoproteina
glycoprotein in Hebrew: גליקופרוטאין
glycoprotein in Macedonian: Гликопротеин
glycoprotein in Malay (macrolanguage): Glikoprotein
glycoprotein in Dutch: Glycoproteïne
glycoprotein in Japanese: 糖タンパク質
glycoprotein in Norwegian: Glykoprotein
glycoprotein in Occitan (post 1500): Glicoproteïna
glycoprotein in Polish: Glikoproteiny
glycoprotein in Portuguese: Glicoproteína
glycoprotein in Russian: Гликопротеины
glycoprotein in Simple English: Glycoprotein
glycoprotein in Finnish: Glykoproteiini
glycoprotein in Swedish: Glykoprotein
glycoprotein in Turkish: Glikoprotein
glycoprotein in Ukrainian: Глікопротеїни
glycoprotein in Chinese: 糖蛋白