Glycosaminoglycans (GAGs) are large complex carbohydrate molecules that interact with a wide variety of proteins involved in physiological and pathological processes. GAGs are also known as mucopolysaccharides due to their viscous, lubricating properties, as found in mucous secretions. GAGs are found on all animal cell surfaces in the extracellular matrix (ECM), and some are known to bind and regulate certain proteins, including chemokines, cytokines, growth factors, morphogens, enzymes and adhesion molecules.
GAGs are linear, sulphated, negatively charged polysaccharides that have molecular weights of approximately 10–100 kDa. GAGs can be divided into two main types. Non‐sulphated GAGs include hyaluronic acid (HA), whereas sulphated GAGs include chondroitin sulphate (CS), dermatan sulphate (DS), keratan sulphate (KS), heparin and heparan sulphate (HS).
GAGs play an important role in cell signaling and development, angiogenesis, axonal growth, tumour progression, metastasis and anti‐coagulation. Uncontrolled progenitor cell proliferation leads to malignant tissue transformation and cancer. GAGs and proteoglycans (PGs) are believed to play a critical role in cell proliferation, acting as co‐receptors for growth factors of the fibroblast growth factor (FGF) family.
PGs are composed of a core protein to which one or more GAG chains are covalently attached. Examples of large PGs are aggrecan, the major PG in cartilage, and versican, which is present in numerous adult tissues such as blood vessels and skin. PGs are known to have a variety of functions, dependent on type and in vivo location, and have important roles in invertebrate and vertebrate development, maintenance, and tissue repair. Many biologically potent small proteins can bind GAG chains as a major part of their function in the ECM, at the cell surface, and also in some intracellular locations. Thus, PGs have become a major focus in research on many diseases.
- References to Glycosaminoglycan (Glycosaminoglycan, sGAG)