英和和英

出典:『Wikipedia』 (2011/05/11 14:18 UTC 版)

英語による解説

引用

Flippases (rarely, flipases) are a family of transmembrane lipid transporter enzymes located in the membrane responsible for aiding the movement of phospholipid molecules between the two leaflets that compose a cell's membrane (transverse diffusion). Their existence was predicted in 1972 by Mark Bretscher, who also named them, to explain how an asymmetric phospholipid bilayer could be formed. Although phospholipids diffuse rapidly in the plane of the membrane, their polar head groups cannot pass easily through the hydrophobic center of the bilayer, limiting their diffusion in this dimension. Phospholipid molecules that are synthesized in the cell are incorporated into the cytoplasmic face of the membrane, where flippases can transfer them to the exoplasmic face. Energy-dependent flippases require energy input in the form of ATP to carry out their function, often known as a flip-flop. However, there are energy-independent flippases which do not require the hydrolysis of ATP and are bidirectional in their action. These energy-independent flippases are responsible for transferring newly sythesised lipids from the outer to the inner leaflet of membranes.