Phospholipid Synthesis 1 Phospholipids are synthesized at the

Phospholipid Synthesis

1. Phospholipids are synthesized at the ER Enzymes in ER help to take precursor molecules and build phospholipids from them If you care about the detail (you don’t have to know for quizzes) see the next slide : )

Figure 9. 17 Synthesis of phospholipids Glycerol phospholipids are synthesized in the ER membrane from cytosolic precursors. Two fatty acids linked to coenzyme A (Co. A) carriers are first joined to glycerol-3 phosphate, yielding phosphatidic acid, which is simultaneously inserted into the membrane. A phosphatase then converts phosphatidic acid to diacylglycerol. The attachment of different polar head groups to diacylglycerol then results in formation of phosphatidylcholine, phosphatidylethanolamine, or phosphatidylserine. Phosphatidylinositol is formed from phosphatidic acid, rather than from diacylglycerol. From: The Endoplasmic Reticulum The Cell: A Molecular Approach. 2 nd edition. Cooper GM. Sunderland (MA): Sinauer Associates; 2000. Copyright © 2000, Geoffrey M Cooper.

2. New Phospholipids become a part of ER membrane

3. When transport vesicles bud off ER, New phospholipids could be a part of it

4. Ribosomes on rough ER may synthesize proteins and embed them in the membrane These integral/ embedded proteins can bud off as vesicles as well

5. Vesicle fuses with Golgi Now the new phospholipids and/or protein is embeded in the membrane of the golgi These can then bud off again as secretory vesicles

6. Secretory vesicle fuses with membrane Now the new phospholipids are apart of the membrane of the cell. Why might the cell need new phospholipids? The budding off of vesicles Endocytosis