Decorin Proteoglycans protein core

DS and CS chains connect to the proteoglycan protein cores by a tetrasac-charide (o-glucuronosyl- (3-1,3-D-galactosyl- (3-1,3-o-galactosyl- (3-1,4-o-xylose). The single GAG chain of decorin is attached, via an O-glycoside link from this xylose, to residue 4 (serine) of the mature protein core (12). 

Scott PG, McEwan PA, Dodd CM, Bergmann EM, Bishop PN, Bella J. Crystal structure of the dimeric protein core of decorin, the archetypal small leucine-rich repeat proteoglycan. Proc Natl Acad Sci USA 2004 101 15633-15638. 

The covalent structure of decorin is illustrated in Fig. 2. This proteoglycan consists of a protein core of a single polypeptide chain of 329 or 330 amino acids (depending on species), close to the Al-terminus of which is usually attached one sulfated GAG chain (12). In chicken, there is a second form of decorin that carries two GAG chains (13). 

The smaller proteoglycans include decorin, biglycan and fibromodulin. They have shorter protein cores and fewer GAG chains than their larger counterparts. Unlike aggregans, these molecules do not affect physical properties of the tissue, but are thought to play a role in cell function and organization of the collagen matrix [64]. 

Klezovitch O, Edelstein C, Zhu L and Scanu AM. Apolipoprotein(a) binds via its C-terminal domain to the protein core of the proteoglycan decorin. Implications for the retention of lipoprotein(a) in atherosclerotic lesions. J Biol Chem 273 23856-65, 1998. 

The proteoglycans in this family, which includes decorin, biglycan, lumican, and fibromodulin, are major components of the interstitial matrix produced by fibroblasts and other cells. The core proteins are small (37-45 kDa) and have several leucine-rich motifs [112] with similarity to the LH-CG receptor, thyrotropin receptor, and Drosophila proteins chaoptin and toll. Core proteins of this family characteristically undergo proteolytic processing following synthesis, with removal of an additional small peptide from the N-terminus. 

Figure 2. A few common CS and DS proteoglycans. Decorin, aggrecan, syndecan-1, and serglycin are represented diagrammatically. Thicker solid lines represent core proteins, with a box toward the C-terminus of syndecan to indicate its transmembrane domain. Thinner solid lines indicate CS or DS chains, and dashed lines are HS chains. For serglycin, the GAG chains may be CS or HS. It is not shown, but aggrecan may also have KS chains, and most proteoglycans will have A-linked oligosaccharides and may have O-linked oligosaccharides.

Rada, J.A., P.K. Comuet, and J.R. Hassell. 1993. Regulation of corneal collagen fibrillogenesis in vitro by comeal proteoglycan (lumican and decorin) core proteins. Exp. Eye Res. 56 635-648. 

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