(see also: cartilage topics)
- proteoglycan is a macromolecule constructed of a protein core to which many glycosaminoglycan chains are attached - protein with bound side chains (glycosaminoglycans);
- to this proteoglycan aggregate, hyaluronic acid is non covalently bound;
- in osteoarthritis, there is a characteristic reduction in a aggregrating proteoglycans;
- about 10% of wt of proteoglycan molecule is protein, and 90% is glycosaminoglycans;
- proteoglycans carry fixed negative charges and attract a high concentration of cations;
- glycans: negatively chondroitin & keratan sulfate repel each other, so that glycosaminoglycan electrostaticrepulsion along chain and between chains and therefore chains assume a fully extended conformation;
- aggrecans (large agregating proteoglycans)
- key proteoglycan molecule in the cartilage matrix and creates the osmotic properties necessary for cartilage to resist compressive loads;
- small proteoglycans (decorin (coats the outside of the collagen fibrils), biglycan, and fibromodulin);
- small glycoprotein serves to stabilize non-covalent association of the proteoglycan subunits with hyaluronic acid in aggregate;
- approximately 100 chondroitin sulfate and 50 keratan sulfate chains are attached;
- major proteoglycan in cartilage, linked to hyaluronan;
- provides unique capacity to bear load and resist compression
- hydrated and thereby allows cartilage to resist a compressive load
- loss of aggrecan is the primary event leading to the destruction of cartilage;
- aggrecanases: enzymes which degrate aggrencans;
- ADAMTS (a disintegrin and metalloproteinase) family of proteinases
- aggrecanase-1 and aggrecanase-2
- The chondrocyte: a cell under pressure.
- Regulation of matrix synthesis rates by the ionic and osmotic environment of articular chondrocytes.
- Synthesis of chondrocytic keratan sulphate-containing proteoglycans by human chondrosarcoma cells in long-term cell culture.
- Ultrastructural modifications of proteoglycans coincident with mineralization in local regions of rat growth plate.
- Electron microscopic studies of cartilage proteoglycans: Direct evidence for the variable length of the chondroitin sulfate-rich region of proteoglycan subunit core protein.
- Assembly of newly synthesized proteoglycan and link protein into aggregates in cultures of chondrosarcoma chondrocytes.
- Specific inhibition of type I and type II collagen fibrillogenesis by the small proteoglycan of tendon.
- Expression of a Wide Range of Extracellular Matrix Molecules in the Tendon and Trochlea of the Human Superior Oblique Muscle