The presentation deals with structure and functions of Proteoglycans and glycoproteins

1. Presented by
Sakshi Saxena
ASU2013010200124
IBT VIth sem

2. www.protein.osaka-u.ac.jp

3. www.protein.osaka-u.ac.jp

4. www.scienceisdelicious.net

5. Proteoglycans are complex extracellular macromolecules consisting of
a multidomain core protein to which is attached one or more
glycosaminoglycan (GAG) chains.

6. Proteoglycans are complex extracellular macromolecules consisting of
a multidomain core protein to which is attached one or more
glycosaminoglycan (GAG) chains.
downhousesoftware.wordpress.com

7. Proteoglycans = GAGs + Core proteins
The GAGs extend perpendicularly from
the core in a brush-like structure.
downhousesoftware.wordpress.com

8. themedicalbiochemistrypage.org

9. The linkage of GAGs to the protein core, in most but not all proteoglycans,
involves a specific tetrasaccharide linker : two galactose (Gal) residues,
and a xylose (Xyl) residue forming a structure such as: GAG(n)–GlcA–Gal–
Gal–Xyl–Ser–protein.
themedicalbiochemistrypage.org

10. The linkage of GAGs to the protein core, in most but not all proteoglycans,
involves a specific tetrasaccharide linker : two galactose (Gal) residues,
and a xylose (Xyl) residue forming a structure such as: GAG(n)–GlcA–Gal–
Gal–Xyl–Ser–protein.

11. Some GAGs are linked to the protein core of proteoglycans via a
trisaccharide linkage that lacks the GlcA residue.
www.cryst.bbk.ac.uk

12. 1. Syndecans
Syndecans constitute a family of transmembrane proteoglycans that perform
multiple functions during development, damage repair, tumor growth,
angiogenesis, and neurogenesis.
The extracellular domain of
syndecans sheds periodically
from the cell membrane. This
process may be stimulated in
response to inflammation,
tissue damage, and other
pathological manifestations.
Cleaved domain may act as
either competitive inhibitor or
activator of signaling cascades
www.glycoforum.gr.jp

13. 2. Glypicans
Glypicans are heparin sulfate proteoglycans involved mainly in regulation of
growth factor signalling -Wnt, Hhs (Hedgehogs), FGF (Fibroblast growth
factor), BMP (bone morphogenic protein).
Extracellular
globular domain.
Can be shed into the
extracellular environment.
Largely through action of the
extracellular lipase which
cleaves the GPI anchor.
www.glycoforum.gr.jp

14. 3. Aggrecans
Aggrecan is a critical component for cartilage structure and the function of joints.
The synthesis and degradation of aggrecan are being investigated for their roles
in cartilage deterioration during joint injury, disease, and aging
www.sigmaaldrich.com
It contains three globular domains, G1, G2, and G3 that are involved in
aggregation, hyaluronan binding, cell adhesion, and chondrocyte apoptosis. This
structural molecule produces a rigid, reversibly deformable gel that resists
compression.

15. 4. Lumican
Lumican is a proteoglycan member of the small leucine-rich proteoglycan (SLRP)
family which is a major keratan sulfate proteoglycan of the cornea and is involved in
collagen fibril organization and circumferential growth, corneal transparency, and
epithelial cell migration and tissue repair.
There are four N-linked sites within the leucine-rich repeat domain of the protein core that can
be substituted with keratan sulfate. The core protein of lumican
(like decorin and fibromodulin) is horseshoe shaped.
onlinelibrary.wiley.com

16. 5. Perlecan
Perlecan is a large heparan sulfate proteoglycan multidomain (five domains,
labeled I-V) proteoglycan that binds to and cross-links many extracellular
matrix (ECM) components and cell-surface molecules
Perlecan is a potent inhibitor of smooth muscle cell proliferation and is thus
thought to help maintain vascular homeostasis. Perlecan can also promote
growth factor (e.g., FGF2) activity and thus stimulate endothelial growth and re-
generation. www.ijdr.in

18. Glycoproteins are proteins that contain oligosaccharide chains
(glycans) covalently attached to polypeptide side-chains.
The attachment process is called glycosylation and is between
a. the hydroxyl (-OH) group of the R group of serine or threonine - called "O-
linked"
b. the amino group (-NH2) in the R group of asparagine - called "N-linked".
Other attachments (rare) are
•In P-glycosylation, sugars are attached to phosphorus on a phosphoserine.
•In C-glycosylation, sugars are attached directly to carbon, such as in the
addition of mannose to tryptophan.

19. www.biology-pages.info

20. oregonstate.edu

21. Dental Biochemistry ; Lecture 45 Carol Lutz, PhD
Complex Carbohydrates: Glycoproteins and Proteoglycans

22. Mucins are a family of high molecular weight,
heavily glycosylated proteins (glycoconjugates) produced
by epithelial tissues
physrev.physiology.org
Mucins' key characteristic is their ability to form gels; therefore they
are a key component in most gel-like secretions, serving functions
from lubrication to cell signaling to forming chemical barriers.

23. Transferrins are iron-binding blood plasma glycoproteins that control the level of
free iron in biological fluids.
Transferin
Proteins Carbohydrate
Amino acids
2 Identical branched
Heteropolysaccharide
chains
Asp
2 sialic
acid
2
galactose
3
mannose
4GlcNac

24. Fibrinogen (factor I) is a glycoprotein in vertebrates that helps in the formation of
blood clots. It is composed of three pairs of polypeptides: two Aa, two Bb, and
two g.
These polypeptides are linked together by 29 disulphide bonds with
polypeptides oriented so all six N-terminal ends meet to form the central E
domain.
www.ebi.ac.uk

25. •Follicle-stimulating hormone (FSH) is
a glycoprotein polypeptide hormone. It is a heterodimer, consisting of
two polypeptide units, alpha and beta.
• The sugar portion of the hormone is covalently bonded to asparagine, and
is composed of N-acetylgalactosamine, mannose, N-
acetylglucosamine, galactose, and sialic acid.
•It regulates the development, growth, pubertal maturation and
reproductive processes of the human body.
Erythropoeitin (EPO) is a hormone
consisting of 193 amino acids in humans
providing a molecular weight of 34,000.
It is highly glycosylated (40% of total
molecular weight) and is responsible for
production of RBCs.
kimbuttbiol4450.blogspot.in

28. •Carbohydrate chains are
negatively charged due to
the presence of sulfate
and uronic acid groups
•Carbohydrate chains may
or may not be negatively
charged
•Glycoproteins are found
mainly in cellular
membranes.
•Proteoglycans are found
mainly in connective
tissues.
• Proteoglycans are
important in
modulation of cellular
development processes
•Glycoproteins
function in cellular
recognition.

29. 1. Proteoglycans : written by: ruth steer from
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notes/31/179/1026
2. GLYCOPROTEINS: AN OVERVIEW M
SHYLAJA and H S SESHADRI accessed
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0307-4412(89)90136-2/pdf
3. STRUCTURE AND FUNCTION OF
TRANSFERRIN M CHING-MING
CHUNG. Accessed from
http://onlinelibrary.Wiley.Com/doi/10.1016/
0307-4412(84)90118-3/pdf
4. Aggrecan and Versican accessed fom
http://www.glycoforum.gr.jp/science/word/
proteoglycan/PGA03E.html
5. Proteoglycans accessed from
http://www.cryst.bbk.ac.uk/pps97/assignme
nts/projects/emilia/Proteoglycans.HTM

30. 6. Structural
Biochemistry/Carbohydrates/Proteoglycans
accessed from
https://en.wikibooks.org/wiki/Structural_Bi
ochemistry/Carbohydrates/Proteoglycans
7. Glycosaminoglycans accessed from
http://themedicalbiochemistrypage.org/glyc
ans.php
8. Carbohydrate Structure of Human
Fibrinogen R. Reid Townsend&, E.
Hilliker‘, Yu-Teh Li&, Roger A. Lainefg,
William R. Bellah, and Yuan Chuan Lee
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CHEMISTRY Prrnted rn [J.S.A Vol. 257.
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