1. SHINGOLIPIDS/ SHINGOPHOSPHOLIPIDS
METABOLISM

2. Role of sphingolipids
Abundant component of myelin sheath (25% in humans)
These lipids are in a continuous state of turnover, defects in this metabolism leads to various diseases

4. SPHINGOLIPIDS AT CELL SURFACES ARE SITES OF BIOLOGICAL RECOGNITION
1. In humans at least 60 different sphingolipids have been identified.
2. Very prominent in neuronal plasma membranes.
3. Carbohydrate moieties of sphingolipids define the human blood groups.
4. The kinds and amounts of gangliosides vary dramatically during development.

5. Sphingolipids
Sphingomyelin contains sphingosine with a long-chain fatty acid attached in amide linkage ( = ceramide)
Ceramide plus a phosphocholine group constitutes a sphingomyelin
Ceramide is also the core component of glycosphingolipids

6. .
The backbone of sphingomyelin is the amino alcohol sphingosine, rather than glycerol (Figure 17.4). A long-chain fatty acid is attached to the amino group of sphingosine through an amide linkage, producing a ceramide .The alcohol group at carbon 1 of sphingosine is esterified to phosphorylcholine, producing SPHINGOMYELIN

8. SIMILARITIES BETWEEN PHOSPHATIDYL CHOLINE
(A GLYCEROPHOSPHOLID) AND SPHINGOMYELIN (A SPHINGOLIPID)
choline
choline
Overall structure is very similar.
Prominent in myelin sheath that surrounds and insulates neurons

9. SPHINGOMYELIN
Sphingomyelin is present in plasma membranes and in lipoproteins
It is very abundant in myelin
Sphingomyelin is abundant in specialized plasma membrane microdomains called LIPID RAFTS

10. LIPID RAFTS
Lipid rafts are specialized microdomains in the plasma membrane that are rich in sphingomyelin and cholesterol
Lipid rafts appear to function in signaling

11. The 3-carbon backbone is analogous to the
SPHINGOLIPIDS
SPHINGOSINE:
a long-chain, unsaturated amino alcohol, a major constituent of sphingolipids, including sphingomyelins.
The 3-carbon backbone is analogous to the
3-carbons of glycerol.
At C3 there is the long chain amino alcohol sphingosine.

12. SPHINGOLIPIDS
At C2 there is a fatty acid which is usually saturated or monounsaturated, and can be either 16,18, 22, or 24 carbons long.

13. SPHINGOLIPIDS
Ceramide is the parent compound. Other polar head groups can be attached at position X.

14. SPHINGOLIPIDS
Glycosphingolipids are a sub-group of sphingolipids that contain sachharide headgroups

15. Glucosyl-ceramide / Glucocerebroside
Monohexoside
Glu
Ceramide
Dihexoside
Gal
Glu
Ceramide
Trihexoside
Gal
Gal
Glu
Ceramide
Biosynthesis of membrane lipids and steroids 1

16. Galactosyl – ceramide / Galactocerebroside
Monohexoside
Gal
Ceramid
Dihexozid
Gal
Gal
Ceramid
Biosynthesis of membrane lipids and steroids 1

17. Biosynthesis of membrane lipids and steroids 1
ABO blood group system
Glu
Gal
GalNAc
Gal
„O” (H) antigen
Fuc
Glu
Gal
GalNAc
Gal
GalNAc
„A” antigen
Fuc
Glu
Gal
GalNAc
Gal
Gal
„B” antigen
Fuc
Biosynthesis of membrane lipids and steroids 1

18. Biosynthesis of membrane lipids and steroids 1
Gangliosides
Glu
GM3
Gal
Ceramide
NANA
GM2
GalNAc
Gal
Glu
Ceramide
NANA
GM1
GalNAc
Gal
Glu
Ceramide
Cholera toxin
Gal
NANA
Biosynthesis of membrane lipids and steroids 1