Related Experiment Video
Updated: Sep 30, 2025

A Fluorescence-based Assay of Phospholipid Scramblase Activity
Published on: September 20, 2016
Conformational changes of a phosphatidylcholine flippase in lipid membranes
Jinkun Xu1, Yilin He2, Xiaofei Wu1
1State Key Laboratory of Membrane Biology, Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China.
Abstract:
Type 4 P-type ATPases (P4-ATPases) actively and selectively translocate phospholipids across membrane bilayers. Driven by ATP hydrolysis, P4-ATPases undergo conformational changes during lipid flipping. It is unclear how the active flipping states of P4-ATPases are regulated in the lipid membranes, especially for phosphatidylcholine (PC)-flipping P4-ATPases whose substrate, PC, is a substantial component of membranes. Here, we report the cryoelectron microscopy structures of a yeast PC-flipping P4-ATPase, Dnf1, in lipid environments. In native yeast lipids, Dnf1 adopts a conformation in which the lipid flipping pathway is disrupted. Only when the lipid composition is changed can Dnf1 be captured in the active conformations that enable lipid flipping. These results suggest that, in the native membrane, Dnf1 may stay in an idle conformation that is unable to support the trans-membrane movement of lipids. Dnf1 may have altered conformational preferences in membranes with different lipid compositions.
Related Concept Videos
Membrane Asymmetry Regulating Transporters
Flippase
Eukaryotic flippases are type-IV P-type ATPases or P4-ATPases belonging to P-type ATPase family proteins that are membrane-bound pumps involved in the ATP-mediated transport of ions and molecules across the membrane. Flippases flip specific phospholipids from the outer to the inner leaflet of a membrane. All P4-ATPases have one...
Membrane Fluidity
Mosaic nature of the membrane
The mosaic characteristic of the membrane helps the plasma membrane remain fluid. The integral proteins and lipids exist as separate but loosely-attached molecules in the membrane. The membrane is...
Phosphoinositides and PIPs
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
Synthesis of Phosphatidylcholine in the ER Membrane
The major components of all eukaryotic cell...
Asymmetric Lipid Bilayer
Fluid Mosaic Model

