Glycoproteins and glycolipids are glycoconjugates that contain carbohydrate chains covalently bonded to lipids or proteins. Glycolipids are composed of a monosaccharide unit joined to a hydrophobic lipid moiety, forming amphiphilic molecules that aggregate in aqueous environments into bilayers, micelles, or lamellar structures. Glycoproteins can be O-linked via hydroxyl side chains of serine or threonine or N-linked via amide nitrogen of asparagine. Glycoproteins function in secretions, cell membranes, and as receptors. Abnormalities in glycoconjugate synthesis can lead to diseases like cancer metastasis.

1. STRUCTURE AND
FUNCTIONS OF
GLYCOPLIPIDS AND
GLYCOPROTEINS
PRESENTED BY.
D.IRENE,
16PGZ001
M.Sc.Zoology (spl in biotechnology),
Lady Doak College,
Madurai

2. INTRODUCTION
CARBOHYDRATE
S
Found in
Plants
Animals
Microbes
Fungi
Stored as
Plants- Starch
Animals- Glycogen
Metabolic
fuel
Glucose
Precursor for
Glycogen
Ribose
Deoxyribose
Galactose
Covalently joined
GLYCOCONJUGATE
Protein-Glycoprotein
Lipid-Glycolipid

3. GLYCOLIPIDS

4. GLYCOLIPIDS
Occurrence

5. Classification of glycolipids
https://www.researchgate.net/figure/236180934_fig6_Fig-6-Common-
types-of-storages-and-membrane-lipids-All-the-lipid-types-shown-have

6. STRUCUTRE OF GLYCOLIPIDS
 Glycoconjugates
 Monosaccharide units joined with a hydrophobic moiety ( ex:acyl glycerol)
 Amphiphilic molecule
 Studied by NMR spectroscopy, X-ray diffraction
electron microscopy.
 Form aggregates in aqueous environment
 Forms include:
Lipid bilayer
Micellar
Lamellar
hexagonal

7. Functions of glycolipids
Functions
As cell junctions
Cell adhesion
to allow metabolites and to
strengthen tissues
In nerve tissues
Glycosphingolipid-Galactosylceramide
Primary lipid in myelin is-galactocerebroside
As receptor
GMI- receptor in human
intestine for cholera
toxin!

10. Phosphatidylcholine (phospholipid) plays a role in membrane-mediated cell signalling
sphingomyelin (sphingolipid) are potent regulators of protein kinases, involved in the
regulation of cell division, differentiation,migration, and programmed cell death.

12. Glycolipid as ABO blood groups

14. GLYCOPROTEINS
Occurrence

15. Classification of glycoproteins
O-linked glycoproteins
(involves hydroxyl side chain of
Ser/Thr and sugar chain such as N-
Acetylgalactoseamine)
N-linked glycoproteins
(involves amide nitrogen of
asparagine and N-
Acetylglucosamine)
Glycosylphosphotidylinosine
anchored glycoproteins
(Linked to carboxy terminal
amino acid of a protein via a
phosphoryl-ethanolamine
moiety joined to an
oligosaccharide which is
linked via glucosamine to
phosphatidylinositol

16. Glycosylphosphatidylinositol linkage

17. Functions of glycoproteins
 Glycoproteins as secretions- Immunoglobulins, FSH,LH, TSH and milk
proteins ex: Lactalbumin.
 Glycoproteins in cell membranes: Glycophorin in RBC
Glycophorin A is the most important attachment site by which the
parasite Plasmodium falciparum invades human red blood cells.

20. Conclusion
 Widely distributed with diverse functionas
 Oligosaccharide chains in the glycoconjugates encode biologic informations
 Important in modulating property of solubility and viscosity.
 Abnormalities in synthesis leads to diseases. (metastatic cancer)
 The field of glycomics provide information on role of sugars in health and diseases
and also indicate targets for drug and other therapies.

21. Questions
 The phospholipid in skin??
 Types of glycolipids??
 O –linked polysaccharide is attached to which amino acid residue??
 What causes the cancer cells to migrate??
 Cell communicates with a help of ??

22. Reference
 https://www.ncbi.nlm.nih.gov/books/NBK21502/
 https://www.ncbi.nlm.nih.gov/pubmed/12553851
 http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/G/Glycoproteins.html
 Robert.T Murray,Harpers illustratyed biochemistry,26th edition,McGraw Hill
publication Inc, 2003,New York,pg-102,110,116,515,527,534,519.
 Richar.T.C Huang,cell adhesionby glycolipids,Nature 276,626
doi:10.1038/276642a0.
 Leffler and Svanborg., Glycoprotiens receptors for uropathogenic E.Coli o
human erythrocytes and uroepithelial cells.,Infect immune 1981
Dec:34(3):920:9.
 Strayer.,Biochemistry, 5th edition. W.H Freeman anf company, pg-464
 Lehinger., Biochemistry, 4th edition, pg 260.