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Biglycan

biglycan
Identifiers
Symbol	BGN
Entrez	633
HUGO	1044
OMIM	301870
RefSeq	NM_001711
UniProt	P21810
Other data
Locus	Chr. X q28

Biglycan is a small leucine-rich repeat proteoglycan (SLRP) which is found in a variety of extracellular matrix tissues, including bone, cartilage and tendon.

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Composition

It consists of a protein core containing leucine-rich repeat regions and two glycosaminoglycan (GAG) chains consisting of either chondroitin sulfate (CS) or dermatan sulfate (DS), with DS being more abundant in most connective tissues. The CS/DS chains are attached at amino acids 5 and 10 in human biglycan.^[1] The composition of the GAG chains has been reported as varying according to tissue of origin. Non-glycanated forms of biglycan (no GAG chains) increase with age in human articular cartilage.^[2]

Nomenclature

The name "biglycan" was proposed in an article by Fisher, Termine and Young in an article in the Journal of Biological Chemistry in 1989 because the proteoglycan contained two GAG chains; formerly it was known as proteoglycan-I (PG-I).^[3]

Diversity

The structure of biglycan core protein is highly conserved across species; over 90% homology has been reported for rat, mouse, bovine and human biglycan core proteins.

Interactions

Biglycan interacts with collagen, both via the core protein and GAG chains ^[4] ^[5]. It has been reported that biglycan interacts more strongly with collagen type II than collagen type I ^[6] ^[7]. Biglycan has been reported to compete with decorin for the same binding site on collagen. ^[8]

Similarity to decorin

The composition of GAG chains of biglycan and decorin originating from the same tissue has been reported to be similar ^[9].

Function

Biglycan is believed to play a role in the mineralisation of bone. Knock-out mice that have had the gene for biglycan suppressed have an osteoporosis-like phenotype with reduced growth rate and lower bone mass than mice that can express biglycan.^[10]

Biglycan core protein binds to the growth factors BMP-4 and influences its bioactivity. ^[11] It has also been reported that the presence of biglycan is necessary for BMP-4 to exert its effects on osteoblasts ^[12]. There is also evidence that biglycan binds to TGF-beta 1

References

^ Roughley PJ and White RJ (1989) Dermatan sulphate proteoglycans of human articular cartilage. The properties of dermatan sulphate proteoglycans I and II. Biochem J 262:823-827.
^ Roughley PJ et al. (1993) Non-proteoglycan forms of biglycan increase with age in human articular cartilage. Biochem J 295:421-426.
^ Fisher LW et al. (1989) Deduced protein sequence of bone small proteoglycan I (biglycan) shows homology with proeoglycan II (decorin) and several nonconnective tissue proteins in a variety of species. J Biol Chem 996:43-48.
^ Schonherr E et al. (1995) Interaction of biglycan with type I collagen. J Biol Chem. 10;270(6):2776-83.
^ Pogany G. et al (1994) The in vitro interaction of proteoglycans with type I collagen is modulated by phosphate. Arch Biochem Biophys. 15;313(1):102-11.
^ Vynios DH et al. (2001) The interactions of cartilage proteoglycans with collagens are determined by their structures. Biochimie. 83(9):899-906.
^ Bidanset D et al. (1992)Binding of the proteoglycan decorin to collagen type VI. J Biol Chem. 15;267(8):5250-6.
^ Schonherr E et al. (1995) Interaction of biglycan with type I collagen. J Biol Chem. 10;270(6):2776-83.
^ Cheng F et al. (1994) Patterns of uronosyl epimerization and 4-/6-O-sulphation in chondroitin/dermatan sulphate from decorin and biglycan of various bovine tissues Glycobiology. 4(5):685-96
^ Xu T et al. (1998) targeted disruption of the biglycan gene leas to an osteoporosis-like phenotype. Nature Genet 20:78-82.
^ Moreno M et al. (2005) Biglycan is a new extracellular component of the Chordin-BMP4 signaling pathway. EMBO J. 6;24(7):1397-405.
^ Chen XD et al. (2004) The small leucine-rich proteoglycan biglycan modulates BMP-4-induced osteoblast differentiation. FASEB J. ;18(9):948-58.

v • d • e Glycoproteins: proteoglycans
Aggrecan - Biglycan - Decorin - Platelet factor 4 - Syndecan 1 - Versican

Category: Proteoglycans

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Biglycan". A list of authors is available in Wikipedia.