Watkins William E, Menon Anant K
Department of Biochemistry, University of Wisconsin-Madison, 53706-1569, USA.
Biol Chem. 2002 Sep;383(9):1435-40. doi: 10.1515/BC.2002.162.
Phospholipid flipping in biogenic membranes is a key feature of membrane bilayer assembly. Flipping is facilitated by proteinaceous transporters (flippases) that do not need metabolic energy to function. No flippase has yet been identified. The architecture of the E. coli protein translocon suggests that it could account for the flippase activity in the bacterial inner membrane. To test this possibility, we used E. coli cells depleted of SecYE or YidC to assay flipping in proteoliposomes reconstituted from detergent extracts of their inner membranes. We conclude that the protein translocon contributes minimally, if at all, to phospholipid flippase activity in the inner membrane.
生物膜中的磷脂翻转是膜双层组装的一个关键特征。翻转由蛋白质转运体（翻转酶）促进，这些转运体发挥功能不需要代谢能量。目前尚未鉴定出翻转酶。大肠杆菌蛋白质转运通道的结构表明，它可能是细菌内膜中翻转酶活性的原因。为了验证这种可能性，我们使用了缺乏SecYE或YidC的大肠杆菌细胞，来测定从其内膜去污剂提取物重构的蛋白脂质体中的翻转情况。我们得出结论，蛋白质转运通道对内膜中磷脂翻转酶活性的贡献（如果有的话）极小。
