Biglycan

Biglycan
250px PDB rendering based on 2ft3.
Available structures PDB Ortholog search: PDBe, RCSB List of PDB id codes 2ft3
Identifiers
Symbols	BGN ; DSPG1; PG-S1; PGI; SLRR1A
External IDs	OMIM: 301870 MGI: 88158 HomoloGene: 1293 GeneCards: BGN Gene
Gene ontology Molecular function • extracellular matrix structural constituent • glycosaminoglycan binding • extracellular matrix binding Cellular component • extracellular region • proteinaceous extracellular matrix • Golgi lumen • cell surface • transport vesicle • extracellular matrix • sarcolemma • lysosomal lumen • extracellular exosome Biological process • blood vessel remodeling • carbohydrate metabolic process • biological_process • peptide cross-linking via chondroitin 4-sulfate glycosaminoglycan • extracellular matrix organization • glycosaminoglycan metabolic process • chondroitin sulfate metabolic process • chondroitin sulfate biosynthetic process • chondroitin sulfate catabolic process • dermatan sulfate biosynthetic process • small molecule metabolic process Sources: Amigo / QuickGO
RNA expression pattern
File:PBB GE BGN 201262 s at tn.png
File:PBB GE BGN 201261 x at tn.png
File:PBB GE BGN 213905 x at tn.png
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	633	12111
Ensembl	ENSG00000182492	ENSMUSG00000031375
UniProt	P21810	P28653
RefSeq (mRNA)	NM_001711	NM_007542
RefSeq (protein)	NP_001702	NP_031568
Location (UCSC)	Chr X: 153.49 – 153.51 Mb	Chr X: 73.48 – 73.5 Mb
PubMed search	[1]	[2]

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 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).

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. 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.

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

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.

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

Interactions

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

Biglycan has been shown to interact with SGCA.

External links

• biglycan at the US National Library of Medicine Medical Subject Headings (MeSH)