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Regulation of phospholipid distribution in the lipid bilayer by flippases and scramblases (Sakuragi & Nagata, in Nat Rev Mol Cel Biol)
Cellular membranes function as permeability barriers that separate cells from the external environment or partition cells into distinct compartments. These membranes are lipid bilayers composed of glycerophospholipids, sphingolipids and cholesterol.
The proteins - flippases and scramblases - mediate this lipid movement between the bilayers. Flippases mediate the confined localization of specific phospholipids (phosphatidylserine (PtdSer) and phosphatidylethanolamine) to the cytoplasmic leaflet. On the other hand, scramblases randomly scramble phospholipids between leaflets and facilitate the exposure of PtdSer on the cell surface, which serves as an important signaling molecule and as an 'eat me' signal for phagocytes. Defects in flippases and scramblases cause various human diseases.
Takaharu Sakuragi and Shigekazu Nagata (Biochemistry & Immunology, IFReC) review the recent research on the structure of flippases and scramblases and their physiological roles.
Prof. Shigekazu Nagata