Mapping bilayer thickness in the ER membrane

Of the three building blocks of life (proteins, lipids and nucleic acids), lipids are one of the most challenging molecules to study. Lipids are the main building blocks of membranes in cells and studying the function of these molecules has been a challenge for scientists for a long time since we lack the tools to study/follow them. Researchers from the laboratory of Yves Barral have developed a novel way to visualize membrane thickness in live cells. Through the use of fluorescently labelled peptide sensors, researchers were able to show for the first time that the membrane of the endoplasmic reticulum (ER) exhibits regions of increased thickness (RITs; Regions of Increased Membrane Thickness). Furthermore, the use of these membrane thickness sensors allowed scientists to demonstrate that the formation of these thicker regions depends on a particular class of lipids, called ceramides and showed that the size of these lipids determines the thickness of these regions and influence the proteins that can reside within them. Importantly, this work demonstrated that these RITs have specific cellular functions such as the formation of membrane contact sites, which are important for the trafficking of various building blocks throughout the cell and in the formation of membrane lateral diffusion barriers at the cleavage plane of the cell, which compartmentalize the ER-membrane into mother and bud domains and confines age to the mother cell.

Link to the paper in external page Science Advances.