What is GAG-DB ?
This database contains the three-dimensional structures of Glycosaminoglycan (GAG) binding proteins that have been crystallized with their ligands. The type of proteins, along with the bound GAG are provided. Links are available to access the information about the original article (Medline), the protein sequence, related structural information (Swissprot, PDB) ....
What are GAGs ?
Glycosaminoglycans are linear, anionic polysaccharides, (GAGs) consisting of repeating disaccharides. Indeed, most GAG chains are formed from repeating disaccharide units of hexosamine and hexuronic acid. The exception is keratan sulfate, whose building blocks consist of hexosamine and galactose. Differences in the structure of the primary disaccharide unit regarding types of uronic acid and hexosamine, the number and position of the sulphate residues, the presence of N-acetyl and/or N-sulphate groups and the relative molecular mass. All such differences bestow these biomolecules' impressive complexity and diversity. The fine structure of the disaccharide units defines the types of GAGs. These include chondroitin/dermatan sulfate (CS/DS), heparin/heparan sulfate (Hep/HS), keratan sulfate (KS) as well as the non-sulfated hyaluronan (HA). GAGs are ubiquitously localized throughout the extracellular matrix (ECM) and to the cell membranes of cells in all tissues. They are either conjugated to protein cores in the form of proteoglycans, e.g., CS/DS, HS, and KS or as free GAGs (HA and Hep). Through their interaction with proteins, GAGs can affect cell-ECM and cell-cell interactions finely modulating ligand-receptor binding and thus chemokine and cytokine activities as well as growth factor sequestration. Indeed, it is well established that GAGs participate in the regulation of all biological processes under homeostasis; they also participate in disease progression.