MBIO 3460 Lecture Notes - Lecture 16: Photobleaching, Atp-Binding Cassette Transporter, Phosphatidylserine
13 Jan 2018
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Document Summary
Understanding lipid polymorphism and how lipid components contribute to phase transitions. Describe how lipids move in membranes, and how specific enzymes can facilitate lipid membrane asymmetry. Most phospholipids can adopt either phase (la or hexll: dependent on temperature and other factors. The phase change temperature is called the tbh: b bilayer, h hexll. Usually there is a lower tbh for unsaturated phospholipids. Lipid membrane asymmetry: due to, asymmetric biosynthesis of lipids, slow, uncatalyzed flip-flop, lipid translocators. Flippases movement: require atp to function, 1 atp: movement of 1 phospholipid, p-type atpase, specifically move phosphatidylethanolamine and phosphatidylserine, moves phospholipids from the extracellular leaflet to the cystolic leaflet, results in an asymmetric distribution of these phospholipids. Important that ps bot be in the outer leaflet: triggers apoptosis, leaves sphingolipids and phosphatidylcholine in the extracellular leaflet. Floppases: moves plasma membrane phospholipids from the cystolic to the extracellular leaflet, abc transporter family, specifically move hydrophobic substances across the plasma membrane, atp dependent.
