MCD BIO 165A Lecture Notes - Lecture 11: Acetyl-Coa, Phosphotransferase, Flippase
22 Nov 2018
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Er makes most lipids: large majority lipids in cell made in er. Except sphingomyelin: initiated in er, completed in golgi. And some glycolipids made exclusively in golgi. And some lipid exclusive to mitochondria & chloroplast: process. 2 fatty acids + coa => acetyl coa (in cytosol) Acyl transferase (part of er membrane) helps insert it into er membrane (outer leaflet, cytosolic) Once acetyl coa in membrane, phosphate aiding insertion (via acyl transferase) removed by phosphatase. Choline phosphotransferase transfers choline group to phospholipid. Flippase balances phospholipid in er membrane -> otherwise outer leaflet has a lot more phospholipid than inner leaflet. Phospholipid synthesis regulated by 4 enzymes: acyl transferase, phosphatase, choline phosphotransferase, flippase. Requires fatty acid (in cytosol) and their activation via coa. The rest happens in er membrane: membrane distributed to organelle thru fusion of vesicles. Within each membrane, lots of enzymes regulate frequency & distribution of distinct phospholipids. Frequency of different types of phospholipids varies in different compartment.
