Structure and functions of glycoplipids and glycoproteins

the role of glycolipids and glycoproteins in living system

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 CARBOHYDRATES 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!

8. 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.

9. Glycolipid as ABO blood groups

10. GLYCOPROTEINS

11. GLYCOPROTEINS Occurrence

12. 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

13. Glycosylphosphatidylinositol linkage STRUCTURES

14. 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.

15. 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.

16. 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 ??

17. 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,26 th 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, 5 th edition. W.H Freeman anf company, pg-464 Lehinger ., Biochemistry, 4 th edition, pg 260.