Opsin is a phospholipid flippase |
| |
Authors: | Menon Indu Huber Thomas Sanyal Sumana Banerjee Sourabh Barré Patrick Canis Sam Warren J David Hwa John Sakmar Thomas P Menon Anant K |
| |
Institution: | 1 Department of Biochemistry, Weill Cornell Medical College, New York, NY 10065, USA 2 Laboratory of Molecular Biology and Biochemistry, The Rockefeller University, New York, NY 10065, USA 3 Sutton Terrace, New York, NY 10065, USA 4 Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA |
| |
Abstract: | Polar lipids must flip-flop rapidly across biological membranes to sustain cellular life 1, 2], but flipping is energetically costly 3] and its intrinsic rate is low. To overcome this problem, cells have membrane proteins that function as lipid transporters (flippases) to accelerate flipping to a physiologically relevant rate. Flippases that operate at the plasma membrane of eukaryotes, coupling ATP hydrolysis to unidirectional lipid flipping, have been defined at a molecular level 2]. On the other hand, ATP-independent bidirectional flippases that translocate lipids in biogenic compartments, e.g., the endoplasmic reticulum, and specialized membranes, e.g., photoreceptor discs 4, 5], have not been identified even though their activity has been recognized for more than 30 years 1]. Here, we demonstrate that opsin is the ATP-independent phospholipid flippase of photoreceptor discs. We show that reconstitution of opsin into large unilamellar vesicles promotes rapid (τ<10 s) flipping of phospholipid probes across the vesicle membrane. This is the first molecular identification of an ATP-independent phospholipid flippase in any system. It reveals an unexpected activity for opsin and, in conjunction with recently available structural information on this G protein-coupled receptor 6, 7], significantly advances our understanding of the mechanism of ATP-independent lipid flip-flop. |
| |
Keywords: | |
本文献已被 ScienceDirect PubMed 等数据库收录! |
|