Glycoprotein (glycoprotein) is a protein containing oligosaccharide chains, which are connected by covalent bonds. The oligosaccharide chain is usually linked to the protein through glycosylation during co-translational modification or post-translational modification.
Glycoproteins are branched
Major carbohydrates found in human glycoproteins
carbohydrate
Types of
abbreviation
With protein
Glycopeptide linkages of glycoproteins, abbreviations
The sugar chains in glycoproteins vary widely and are rich in structural information.
Carry information on protein metabolism
Glycoprotein
Glycoprotein is a sugar-containing protein, which is formed by oligosaccharide chain and certain amino acid residues in peptide chain covalently linked by glycosidic bonds.
Glycoprotein formation in cells
Its main biological function is biological recognition of cells or molecules. For example, sperm need to recognize the corresponding glycoprotein on the egg cell membrane when the egg is fertilized. Receptor proteins and tumor cell surface antigens are also glycoproteins. Glycoproteins are commonly found in animals, plants, and microorganisms, with a wide range of functions and a wide range of functions. They can be divided into three categories according to their existence:
1. Soluble glycoproteins exist in intracellular fluid, various body fluids and mucus secreted by luminal glands. Plasma proteins are glycoproteins except albumin. Soluble glycoproteins include enzymes (such as nucleases, proteases, glycosidases), peptide hormones (such as chorionic gonadotropin, luteinizing hormone, thyroid stimulating hormone, erythropoietin), antibodies, complement, and Some growth factors, interferons, somatostatin, lectins and toxins.
2. Membrane-bound glycoprotein, the peptide chain of which consists of a hydrophobic peptide and a hydrophilic peptide. The number of hydrophobic peptides can be one to several, and they are embedded in the membrane lipid bilayer through hydrophobic interaction. The hydrophilic peptide is exposed outside the membrane. The sugar chain is attached to the hydrophilic peptide and has strict directionality. On the surface of the plasma membrane, the sugar chains all face outwards; on the inner membrane of the cells, they generally face the cavity. Membrane-bound glycoproteins include enzymes, receptors, lectins, and transporters. Such glycoproteins are often involved in cell recognition and can serve as surface markers or surface antigens for specific cells or cells at specific stages.
3. Structural glycoprotein, which is an insoluble macromolecular glycoprotein in the extracellular matrix,
Glycoprotein
Such as collagen and various non-collagen glycoproteins (fibronectin, laminin, etc.). Their function is not only to support, connect and buffer the structural components of the extracellular matrix, but also to participate in cell recognition, adhesion and migration, and to regulate cell proliferation and differentiation.
An oligosaccharide chain generally refers to a polymer formed by glycoside linkages of 2 to 10 monosaccharide groups. The oligosaccharide chains of glycoproteins are often branched. Because the terminal carbon (anomeric carbon) atoms of monosaccharides have two configurations of and , and there are multiple hydroxyl groups that can form glycosidic bonds in the monosaccharide molecule, the diversity of sugar chain structures exceeds that of polynucleotides and Peptide chain. Sufficient identification information can be stored in the sugar chain structure, so it plays a decisive role in molecular recognition and cell recognition. The physiological functions involved in glycoproteins include coagulation, immunity, secretion, endocytosis, material transport, information transmission, regulation of nerve conduction, growth and differentiation, cell migration, cell homing, wound repair and regeneration, etc. The glycoprotein sugar chain also participates in maintaining its peptide chain in a biologically active natural conformation and stabilizes the peptide chain structure, and gives the entire glycoprotein molecule specific physical and chemical properties (such as lubricity, viscoelasticity, resistance to heat inactivation, and resistance to proteases Hydrolysis and freeze resistance, etc.).
Glycoproteins are associated with many diseases such as infections, tumors, cardiovascular disease, liver disease, kidney disease, diabetes and some
Glycoprotein
It is related to the occurrence and development of hereditary diseases. In addition, glycoproteins and glycolipids on the cell surface can "shed off" to the surrounding environment or enter the blood circulation. They can serve as signs of abnormalities to provide information for clinical diagnosis. Glycoproteins in body fluids often have specific or Strong or weak changes, which can help diagnosis or prognosis. Glycoproteins are also increasingly involved in treatment. For example, antibodies directed against specific sugar structures on the surface of specific cells can be used as targeted carriers for therapeutic drugs. The use of sugars (monosaccharides, oligosaccharides or glycopeptides) to fight infection and metastasis has also emerged. [1]
