Mutations in fibrillin result in Marfan s syndrome , a genetic disorder that affects elastic tissues. Marfan s patients are prone to aneurisms and aortic rupture. Overall, it has the physical properties of a viscous fluid or gel. Major constituents of the ground substance are glycosaminoglycans, proteoglycans and glycoproteins. GAGs are highly charged, polyannionic molecules, due to an abundance of carboxyl, hydroxyl and sulfate groups.
Some GAGs form electrostatic interactions with collagens, which carry a net positive charge.
HA serves a lubricative function in the synovial fluid of joints. Many pathogenic bacteria produce hyaluronidase, which reduces the viscosity of the ground substance and thus facilitates invasiveness. PGs can form aggregate structures with other PGs and structural glycoproteins to form enormous macromolecular assemblies. Glycoproteins of the ECM include the collagens and a number of structurally diverse, multi-functional molecules, e.g., laminin and fibronectin . Some of these molecules support cell adhesion and migration.