Biology:Biglycan
 Generic protein structure example |
Biglycan is a small leucine-rich repeat proteoglycan (SLRP) which is found in a variety of extracellular matrix tissues, including bone, cartilage and tendon. In humans, biglycan is encoded by the BGN gene[1] which is located on the X chromosome.
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).[2]
Structure
Biglycan 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.[3] 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.[4]
The composition of GAG chains of biglycan and decorin originating from the same tissue has been reported to be similar.[5]
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.
Function
Biglycan is believed to play a role in the mineralization of bone. Knock-out mice that have had the gene for biglycan suppressed (Bgn -/-) have an osteoporosis-like phenotype with reduced growth rate and lower bone mass than mice that can express biglycan.[6]
Biglycan core protein binds to the growth factors BMP-4 and influences its bioactivity.[7] It has also been reported that the presence of biglycan is necessary for BMP-4 to exert its effects on osteoblasts.[8] There is also evidence that biglycan binds to TGF-beta 1.
Interactions
Biglycan interacts with collagen, both via the core protein and GAG chains.[9][10] It has been reported that biglycan interacts more strongly with collagen type II than collagen type I.[11][12] Biglycan has been reported to compete with decorin for the same binding site on collagen.[9]
Biglycan has been shown to interact with SGCA.[13]
Biglycan is a particularly important proteoglycan for binding to lipoprotein in human blood vessels, thus being a significant cause of atherosclerosis.[14]
References
- ↑ "Fine mapping of the human biglycan (BGN) gene within the Xq28 region employing a hybrid cell panel". Genomics 13 (2): 481–3. June 1992. doi:10.1016/0888-7543(92)90279-2. PMID 1612609.
- ↑ "Deduced protein sequence of bone small proteoglycan I (biglycan) shows homology with proteoglycan II (decorin) and several nonconnective tissue proteins in a variety of species". J. Biol. Chem. 264 (8): 4571–6. March 1989. doi:10.1016/S0021-9258(18)83781-4. PMID 2647739.
- ↑ "Dermatan sulphate proteoglycans of human articular cartilage. The properties of dermatan sulphate proteoglycans I and II". Biochem. J. 262 (3): 823–7. September 1989. doi:10.1042/bj2620823. PMID 2590169.
- ↑ "Non-proteoglycan forms of biglycan increase with age in human articular cartilage". Biochem. J. 295 (2): 421–6. October 1993. doi:10.1042/bj2950421. PMID 8240239.
- ↑ "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. October 1994. doi:10.1093/glycob/4.5.685. PMID 7881183.
- ↑ "Targeted disruption of the biglycan gene leads to an osteoporosis-like phenotype in mice". Nature Genetics 20 (1): 78–82. September 1998. doi:10.1038/1746. PMID 9731537.
- ↑ "Biglycan is a new extracellular component of the Chordin-BMP4 signaling pathway". EMBO J. 24 (7): 1397–405. April 2005. doi:10.1038/sj.emboj.7600615. PMID 15775969.
- ↑ "The small leucine-rich proteoglycan biglycan modulates BMP-4-induced osteoblast differentiation". FASEB J. 18 (9): 948–58. June 2004. doi:10.1096/fj.03-0899com. PMID 15173106.
- ↑ 9.0 9.1 "Interaction of biglycan with type I collagen". J. Biol. Chem. 270 (6): 2776–83. February 1995. doi:10.1074/jbc.270.6.2776. PMID 7852349.
- ↑ "The in vitro interaction of proteoglycans with type I collagen is modulated by phosphate". Archives of Biochemistry and Biophysics 313 (1): 102–11. August 1994. doi:10.1006/abbi.1994.1365. PMID 8053669.
- ↑ "The interactions of cartilage proteoglycans with collagens are determined by their structures". Biochimie 83 (9): 899–906. September 2001. doi:10.1016/S0300-9084(01)01332-3. PMID 11698112.
- ↑ "Binding of the proteoglycan decorin to collagen type VI". J. Biol. Chem. 267 (8): 5250–6. March 1992. doi:10.1016/S0021-9258(18)42759-7. PMID 1544908. http://www.jbc.org/cgi/reprint/267/8/5250.
- ↑ "The small leucine-rich repeat proteoglycan biglycan binds to alpha-dystroglycan and is upregulated in dystrophic muscle". J. Cell Biol. 148 (4): 801–10. 2000. doi:10.1083/jcb.148.4.801. PMID 10684260.
- ↑ "Retention of atherogenic lipoproteins in the artery wall and its role in atherogenesis". Nutrition, Metabolism, and Cardiovascular Diseases 22 (1): 1–7. 2012. doi:10.1016/j.numecd.2011.09.007. PMID 22176921. http://www.nmcd-journal.com/article/S0939-4753(11)00227-4/pdf.
External links
- biglycan at the US National Library of Medicine Medical Subject Headings (MeSH)
- Human BGN genome location and BGN gene details page in the UCSC Genome Browser.
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