Related Experiment Video
Updated: Jul 11, 2026

10:58
PIP-on-a-chip: A Label-free Study of Protein-phosphoinositide Interactions
Published on: July 27, 2017
Complexation of integral membrane proteins by phosphorylcholine-based amphipols
1Department of Chemistry and Faculty of Pharmacy, Université de Montréal, CP 6128 Succursale Centre Ville, Montreal QC, Canada.
Biochimica Et Biophysica Acta
|September 11, 2007
Summary
New phosphorylcholine-based amphipols (PC-amphipols) offer improved stability for membrane proteins like bacteriorhodopsin (BR) in aqueous solutions, outperforming traditional detergents.
Area of Science:
- Biochemistry
- Polymer Chemistry
- Structural Biology
Background:
- Integral membrane proteins require detergents or amphipols for solubilization in aqueous solutions.
- Conventional amphipols have limitations in solubility under various conditions.
- A need exists for novel amphipols with enhanced stability and broader applicability.
Purpose of the Study:
- To develop and characterize novel amphipols based on phosphorylcholine (PC) units.
- To evaluate the efficacy of PC-amphipols in stabilizing membrane proteins.
- To compare the performance of PC-amphipols with existing amphipols and detergents.
Main Methods:
- Synthesis and characterization of four distinct PC-amphipols.
- Solubilization and complexation of membrane proteins (cytochrome b(6)f and bacteriorhodopsin).
- Assessment of complex stability using rate zonal ultracentrifugation and isothermal titration calorimetry.
Main Results:
- PC-amphipols demonstrated superior solubility in aqueous media across a range of pH, salt concentrations, and divalent ion presence.
- Short PC-amphipols (approx. 22 kDa) with specific compositions (30% octyl, 35% PC, 35% isopropyl) effectively stabilized bacteriorhodopsin (BR).
- BR/PC-amphipol complexes maintained native state and solubility under challenging conditions (pH ≥ 5, 1 M NaCl, 12 mM Ca2+).
Conclusions:
- PC-amphipols represent a significant advancement over conventional amphipols and detergents for membrane protein handling.
- The developed PC-amphipols enhance protein stability and solubility, preserving the native state of membrane proteins.
- These findings pave the way for broader applications of amphipols in membrane protein research and biotechnology.
Related Concept Videos
Membrane Proteins
Plasma membranes have integral transmembrane proteins involved in facilitated transport. These proteins are collectively referred to as transport proteins, and they function as either channels for the material or as carriers themselves. Channel proteins have hydrophilic domains exposed to the intracellular and extracellular fluids and a hydrophilic channel through their core that provides a hydrated opening for solutes to pass through the membrane layers. Passage through the channel allows...
Introduction to Membrane Proteins
The cell membrane, or plasma membrane, is an ever-changing landscape. It is described as a fluid mosaic where various macromolecules are embedded in the phospholipid bilayer. Among the macromolecules are proteins. The protein content varies across cell types. For example, mitochondrial inner membranes contain ~76% protein content, while myelin contains ~18% protein content. Individual cells contain many types of membrane proteins—red blood cells contain over 50—and different cell types have...
Synthesis of Phosphatidylcholine in the ER Membrane
The ER synthesizes lipids for building cell membranes and performing cellular functions such as energy storage and signaling. The lipid synthesis machinery embedded in the ER membrane primarily collects all reactants from the cytosol. Following synthesis, the secretory pathway and the ER contact sites distribute these lipids to other cellular organelles. Additionally, the energy-rich triacylglycerides are transported from the ER via lipid droplets.
The major components of all eukaryotic cell...
The major components of all eukaryotic cell...
Phosphoinositides and PIPs
Phosphoinositides are a group of phospholipids containing a glycerol backbone with two fatty acid chains and a phosphate attached to a myoinositol sugar ring. The inositol head group extends into the cytoplasm, where it is modified by adding phosphate groups to form phosphatidylinositol phosphates or PIPs.
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
Lipids as Anchors
In the plasma membrane, the lipids forming the bilayer can also act as an anchor to tether proteins to the membrane. The three main types of lipid anchors found in eukaryotes are – prenyl groups, fatty acyl groups, and glycosylphosphatidylinositol or GPI groups. Prenyl and fatty acyl groups act as anchors on the cytosolic surface of the membrane, whereas GPI anchors proteins on the extracellular side.
The carboxy-terminal of most of the prenylated proteins, such as Ras proteins, contains the...
The carboxy-terminal of most of the prenylated proteins, such as Ras proteins, contains the...
Mechanisms of Membrane Domain Formation
Different physical properties of lipids and proteins allow them to localize and form distinct islands or domains in the membrane. Some membrane domains are formed due to protein-protein interactions, whereas others are formed due to the presence of specific lipids such as sphingolipids and sterols—for example, large proteins, such as bacteriorhodopsin, aggregate and create distinct domains.
Another mechanism for membrane domain formation involves membrane proteins interacting with cytoskeletal...
Another mechanism for membrane domain formation involves membrane proteins interacting with cytoskeletal...

