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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/04/06 15:23:51」(JST)

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Not to be confused with bacterial peptidoglycan.

Aggrecan, the major proteoglycan in cartilage, has 2316 amino acids

Proteoglycans are proteins^[1] that are heavily glycosylated. The basic proteoglycan unit consists of a "core protein" with one or more covalently attached glycosaminoglycan (GAG) chain(s).^[2] The point of attachment is a Ser residue to which the glycosaminoglycan is joined through a tetrasaccharide bridge (e.g. chondroitin sulfate-GlcA-Gal-Gal-Xyl-PROTEIN). The Ser residue is generally in the sequence -Ser-Gly-X-Gly- (where X can be any amino acid residue but Proline), although not every protein with this sequence has an attached glycosaminoglycan. The chains are long, linear carbohydrate polymers that are negatively charged under physiological conditions due to the occurrence of sulfate and uronic acid groups. Proteoglycans occur in the connective tissue.

Types

Proteoglycans can be categorised depending upon the nature of their glycosaminoglycan chains. Proteoglycans can also be categorised by size, usually in atomic mass units or kiloDaltons (kDa), similar to non-glycosylated proteins.

Types include:

Glycosaminoglycans	Small proteoglycans	Large proteoglycans
chondroitin sulfate/dermatan sulfate	decorin, 36 kDa biglycan, 38 kDa	versican, 260-370 kDa, present in many adult tissues including blood vessels and skin
heparan sulfate/chondroitin sulfate	testican, 44 kDa	perlecan, 400-470 kDa
chondroitin sulfate	bikunin, 25 kDa	neurocan, 136 kDa aggrecan, 220 kDa, the major proteoglycan in cartilage
keratan sulfate	fibromodulin, 42 kDa lumican, 38 kDa

Certain members are considered members of the "small leucine-rich proteoglycan family" (SLRP).^[3] These include decorin, biglycan, fibromodulin and lumican.

Function

Proteoglycans are a major component of the animal extracellular matrix, the "filler" substance existing between cells in an organism. Here they form large complexes, both to other proteoglycans, to hyaluronan, and to fibrous matrix proteins (such as collagen). They are also involved in binding cations (such as sodium, potassium and calcium) and water, and also regulating the movement of molecules through the matrix. Evidence also shows they can affect the activity and stability of proteins and signalling molecules within the matrix.^{[citation needed]} Individual functions of proteoglycans can be attributed to either the protein core or the attached GAG chain and serve as lubricants.

Synthesis

The protein component of proteoglycans is synthesized by ribosomes and translocated into the lumen of the rough endoplasmic reticulum. Glycosylation of the proteoglycan occurs in the Golgi apparatus in multiple enzymatic steps. First a special link tetrasaccharide is attached to a serine side chain on the core protein to serve as a primer for polysaccharide growth. Then sugars are added one at a time by glycosyl transferase. The completed proteoglycan is then exported in secretory vesicles to the extracellular matrix of the tissue.

Proteoglycans and disease

An inability to break down proteoglycans is characteristic of a group of genetic disorders, called mucopolysaccharidoses. The inactivity of specific lysosomal enzymes that normally degrade glycosaminoglycans leads to the accumulation of proteoglycans within cells. This leads to a variety of disease symptoms, depending upon the type of proteoglycan that is not degraded.

References

^ Proteoglycans at the US National Library of Medicine Medical Subject Headings (MeSH)
^ Gerhard Meisenberg; William H. Simmons (2006). Principles of medical biochemistry. Elsevier Health Sciences. pp. 243–. ISBN 978-0-323-02942-1. Retrieved 6 February 2011.
^ Hans-Joachim Gabius; Sigrun Gabius (February 2002). Glycosciences: Status and Perspectives. John Wiley and Sons. pp. 209–. ISBN 978-3-527-30888-0. Retrieved 6 February 2011.

External links

Diagram at nd.edu
Diagram at usip.edu

UpToDate Contents

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English Journal

Biological effects of the plant-derived polyphenol resveratrol in human articular cartilage and chondrosarcoma cells.

Im HJ, Li X, Chen D, Yan D, Kim J, Ellman MB, Stein GS, Cole B, Kc R, Cs-Szabo G, van Wijnen AJ.SourceDepartment of Biochemistry, Rush University Medical Center, Chicago, Illinois; Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, Illinois; Department of Rheumatology, Rush University Medical Center, Chicago, Illinois. hee-jeong_sampen@rush.edu.
Journal of cellular physiology.J Cell Physiol.2012 Oct;227(10):3488-97. doi: 10.1002/jcp.24049.
The natural phytoestrogen resveratrol (RSV) may have therapeutic potential for arthritic conditions. RSV is chondroprotective for articular cartilage in rabbit models for arthritis, but its biological effects on human articular cartilage and chondrosarcoma cells are unknown. Effects of RSV on human
PMID 22252971

Molecular shuttle between extracellular and cytoplasmic space allows for monitoring of GAG biosynthesis in human articular chondrocytes.

Hoshi H, Shimawaki K, Takegawa Y, Ohyanagi T, Amano M, Hinou H, Nishimura S.SourceField of Drug Discovery Research, Faculty of Advanced Life Science and Graduate School of Life Science, Hokkaido University, N21, W11, Kita-ku, Sapporo 001-0021, Japan.
Biochimica et biophysica acta.Biochim Biophys Acta.2012 Sep;1820(9):1391-8. Epub 2012 Jan 14.
BACKGROUND: Cell surface proteoglycans play vital functional roles in various biological processes such as cell proliferation, differentiation, adhesion, inflammation, immune response, sustentation of cartilage tissue and intensity of tissues. We show here that serglycin-like synthetic glycopeptides
PMID 22265686

Japanese Journal

巨大糖タンパク質プロテオグリカンの小角X線散乱測定による特性解析

渡邊康
食品総合研究所研究報告 (79), 41-45, 2015-03
NAID 40020459783

Mechanisms for modulation of neural plasticity and axon regeneration by chondroitin sulphate (Fundamental Roles of Glycans in Eukaryotes)

Miyata Shinji,Kitagawa Hiroshi
The journal of biochemistry 157(1), 13-22, 2015-01
NAID 40020325350

サケ軟骨プロテオグリカンにおける上皮成長因子様作用の証明

葛西宏介,藤田沙耶花,石川孝 [他]
保健科学研究 Journal of health science research 5, 93-104, 2015
NAID 40020411176

Related Pictures

★リンクテーブル★

リンク元	「グリコサミノグリカン」「プロテオグリカン」
拡張検索	「chondroitin sulfate proteoglycan」「sulfated proteoglycan」

「グリコサミノグリカン」

　　[★]

英: glycosaminoglycan
同: ムコ多糖 mucopolysaccharide
関: プロテオグリカン proteoglycan、コンドロイチン硫酸、酸性ムコ多糖体症、多糖、デルマタン硫酸

概念

細胞間マトリックスを埋める多糖
粘稠性と弾力性が高い粘液
枝分かれのない多糖で、ウロン酸(uronic acid)とヘキソサミン残基(アミノ糖 amino sugar)が交互につながっている
グリコサミノグリカンがタンパク質に結合した化合物がプロテオグリカン

グリコサミノグリカン + 蛋白質　＝　プロテオグリカン

グリコサミノグリカン	ウロン酸	ヘキソサミン残基	結合			局在	-COO^-	-SO₃^-
ヒアルロン酸	D-グルクロン酸	N-アセチル-D-グルコサミン	GlcUA	β1-3	GlcNAc	硝子体、関節液、臍帯	1	0
コンドロイチン4-硫酸	D-グルクロン酸	N-アセチル-D-ガラクトサミン 4-硫酸	GlcUA	β1-3	GalNAc	骨、象牙質、軟骨	1	1
コンドロイチン6-硫酸	D-グルクロン酸	N-アセチル-D-ガラクトサミン 6-硫酸	GlcUA	β1-3	GalNAc	骨、象牙質、軟骨	1	1
デルマタン硫酸	L-イズロン酸	N-アセチル-D-ガラクトサミン 4-硫酸	IdoA	β1-3	GalNAc	皮膚、動脈壁、腱、骨、象牙質	1	1
ケラタン硫酸	D-ガラクトース	N-アセチル-D-グルコサミン 6-硫酸	Gal	β1-4	GlcNAc	軟骨、椎間板、角膜	0	1
ヘパリン	L-イズロン酸 2-硫酸	N-スルホ-D-グルコサミン 6-硫酸	IdoA	α1-4	GlcNAc	小腸、筋肉、肺、脾、腱、肝、肥満細胞	1	3