Heparan

There are other glycosaminoglycans. Hyaluronic acid [9004-61-9] occurs both free and in noncovalent association with proteoglycan molecules. Heparin [9005-49-6] and heparan sulfate [39403-40-2] also known as heparitin sulfate [9050-30-0] occur in mast cells and in the aorta, Hver, and lungs. 

CS, chondroitin sulfate DS, dermatan sulfate HS, heparan sulfate (an analog of heparin) ... 

Danaparoid (Orgaran mean MW, 6,000 Da) is a mixture of nonheparin glycosaminoglycans derived from pig gut (dermatan sulfate, heparan sulfate, chondroitin sulfate). Die anti-Xa/anti-IIa ratio (22 1) is even greater than seen with LMWH. Die anti-IIa effect may be mediated in part by dermatan sulfate, which catalyzes thrombin inhibition by heparin cofactor II. 

FGF (22 members) FGFs require heparan sulfate to activate their receptors FGFR Four members expressed as a number of splice variants Proliferation of many cell types. Embryo patterning and organogenesis, bone development, angiogenesis... 

Syndecans are transmembrane proteins, which are modified by the addition of heparan sulphate glycos-aminoglycan (GAG) chains and other sugars. Syndecans bind a wide variety of different ligands via their heparan sulphate chains. Binding specificities may vary depending on cell-type specific modifications of the heparan sulphate chains. 

Basal laminas are specialized areas of the ECM that surround epithelial and some other cells (eg, muscle cells) here we discuss only the laminas found in the renal glomerulus. In that strucmre, the basal lamina is contributed by two separate sheets of cells (one endothelial and one epithelial), each disposed on opposite sides of the lamina these three layers make up the glomerular membrane. The primary components of the basal lamina are three proteins—laminin, entactin, and type IV collagen—and the GAG heparin or heparan sulfate. These components are synthesized by the underlying cells. 

Heparan sulfate GlcN, GlcUA GlcN Xyl-Ser Skin fibroblasts, aortic wall... 

Mucopolysaccharidoses Hurler, Scheie, MPSI a-L-lduronidase Dermatan sulfate, heparan sulfate... 

Sanfilippo A MPS IIIA Heparan sulfate N-sulfatase Heparan sulfate... 

Certain proteoglycans (eg, heparan sulfate) are associated with the plasma membrane of cells, with their core proteins acmally spanning that membrane. In it they may act as receptors and may also participate in the mediation of cell growth and cell-cell communication. The attachment of cells to their substramm in cul-mre is mediated at least in part by heparan sulfate. This proteoglycan is also found in the basement membrane of the kidney along with type IV collagen and laminin... 

Hyaluronic acid may be important in permitting tumor cells to migrate through the EGM. Tumor cells can induce fibroblasts to synthesize greatly increased amounts of this GAG, thereby perhaps facifitating their own spread. Some mmor cells have less heparan sulfate at their surfaces, and this may play a role in the lack of adhesiveness that these cells display. 

The intima of the arterial wall contains hyaluronic acid and chondroitin sulfate, dermatan sulfate, and heparan sulfate proteoglycans. Of these proteoglycans, dermatan sulfate binds plasma low-density lipoproteins. In addition, dermatan sulfate appears to be the major GAG synthesized by arterial smooth muscle cells. Because it is these cells that profiferate in atherosclerotic lesions in arteries, dermatan sulfate may play an important role in development of the atherosclerotic plaque. 

The major GAGs are hyaluronic acid, chondroitin 4- and 6-sulfates, keratan sulfates I and II, heparin, heparan sulfate, and dermatan sulfate. 

Fig. 34.—Circular Dichroism of Glycosaminoglycans (a) Hyaluronic Acid (b) Heparan Sulfate from Normal Mammalian Tissue (c) Chondroitin 4-Sulfate (d) Dermatan Sulfate ...

EC-SOD is a copper-zinc enzyme located on endothelial cell surfaces. It is believed that EC-SOD binds to the vasculature via specific glycosaminoglycans — probably heparan sulphate on the endothelium. The association of EC-SOD with endothelial cell surfaces may indicate a cell-specific protective role. Eig/ity per cent of SOD activity in control, noninflamed synovial fluid is due to EC-SOD and its concentration is decreased by 50% in RA fluid (Marklund etal., 1986). 

HRA Histamine-releasing activity HRAN Neutrophil-derived histamine-releasing activity HRf Homologous-restriction factor HRF Histamine-releasing factor HRP Horseradish peroxidase HSA Human serum albumin HSP Heat-shock protein HS-PG Heparan sulphate protet ycan... 

Carvalho, R. S. H., Tersariol, I. L. S., Nader, H., and Nakaie, C. R., First purification of heparan sulfate disaccharides with an amine resin used as solid support for peptide synthesis, Anal. Chim. Acta, 403, 205, 2000. 

---