Pomorski T, Menon A K
Humboldt University Berlin, Institute of Biology/Biophysics, Invalidenstr. 43, 10115, Berlin, Germany.
Cell Mol Life Sci. 2006 Dec;63(24):2908-21. doi: 10.1007/s00018-006-6167-7.
The typically distinct phospholipid composition of the two leaflets of a membrane bilayer is generated and maintained by bi-directional transport (flip-flop) of lipids between the leaflets. Specific membrane proteins, termed lipid flippases, play an essential role in this transport process. Energy-independent flippases allow common phospholipids to equilibrate rapidly between the two monolayers and also play a role in the biosynthesis of a variety of glycoconjugates such as glycosphingolipids, N-glycoproteins, and glycosylphosphatidylinositol (GPI)-anchored proteins. ATP-dependent flippases, including members of a conserved subfamily of P-type ATPases and ATP-binding cassette transporters, mediate the net transfer of specific phospholipids to one leaflet of a membrane and are involved in the creation and maintenance of transbilayer lipid asymmetry of membranes such as the plasma membrane of eukaryotes. Energy-dependent flippases also play a role in the biosynthesis of glycoconjugates such as bacterial lipopolysaccharide. This review summarizes recent progress on the identification and characterization of the various flippases and the demonstration of their biological functions.
膜双层两个小叶典型的独特磷脂组成是由脂质在小叶之间的双向转运（翻转）产生并维持的。特定的膜蛋白，即脂质翻转酶，在这一转运过程中起着至关重要的作用。不依赖能量的翻转酶使常见磷脂能在两个单层之间迅速达到平衡，并且在多种糖缀合物（如糖鞘脂、N-糖蛋白和糖基磷脂酰肌醇（GPI）锚定蛋白）的生物合成中也发挥作用。依赖ATP的翻转酶，包括P型ATP酶和ATP结合盒转运蛋白保守亚家族的成员，介导特定磷脂向膜的一个小叶的净转移，并参与真核生物质膜等膜的跨双层脂质不对称性的产生和维持。依赖能量的翻转酶在细菌脂多糖等糖缀合物的生物合成中也发挥作用。本综述总结了各种翻转酶的鉴定和表征及其生物学功能证明方面的最新进展。
