Synthesis of Membrane Lipids

Synthesis of Membrane Lipids

1. Synthesis of Membrane Lipids Vignesh. O

2. Membrane Lipids Lipids involved in forming the structure of biological membranes. Assembled from phosphoglycerides, sphingolipids and steroids. Arranged in bilayers. Amphipathic molecules.

3. Synthesis Occurs in endomembrane compartment (incl. the domain of golgi and ER). Specialized phospholipids are synthesized in mtc and peroxisomes. Includes the activity of hundreds of enzymes. Active transport (free diffusion denied due to hydrophobicity).

4. Phosphoglycerides Most abundant class. Derivatives of glycerol-3-phosphate. Contains 2 fatty acyl chains (esterified to -OH) and polar head group(attached to phosphate). Classified according to head group. Eg : Phosphatidylcholine ( Lecithin ) – Choline head group. Phosphatidylethanolamine ( Cephalin ) – Ehanolamine head group.

5. Plasmalogens Phosphoglycerides with ester and ether linkage. Ester linkage (C-OOC) between fatty acyl group and glycerol. Ether linkage ( C-O-C ) between long HC chain and glycerol. Constitute 20% of phosphoglycerides.

6. Sphingolipids Compounds derived from sphingosine ( aminoacyl alcohol). Eg . Sphingomyelin ( phosphocholine attached to terminal hydroxyl group) - Most abundant sphingolipid

7. Gangliosides Complex glyco sphingolipid . Contains 1 or 2 sugar chains attached to sphingosine .

8. Steroids Cholesterol and derivatives. Steroid nucleus. Cholestrol abundant in plasma membranes of mammalian cells but absent in prokaryotes. Amphipathic (Since –OH group interact with water)

9. Synthesis of membrane lipids Why? Cells can’t divide and enlarge. Important as protein synthesis and DNA replication . Synthesize new membrane by the expansion of existing membranes. Early synthesis occurs in the cytoplasm. Final steps are catalyzed by pre-existing membrane bound enzymes.

10. Fatty acids are the key components of membrane lipids

11. Fatty acids are the key components of membrane lipids FA synthesis regulation plays major role in membrane synthesis also.