Membranes really know how to mingle. They are dynamic in the cell—budding away from one organelle to fuse with another, remodeling themselves for the situation. My awkward party persona should take some notes…I’ve never seen membranes hang out next to the Chex Mix bowl all night. Today’s image is from a recent paper on membrane scission and the role of membrane remodeling proteins. The membranes that compartmentalize a cell’s organelles are under constant transformation. Membrane sculpting is a coordinated process that includes bending membranes and remodeling by fission and fusion (severing and joining, respectively). Membrane curvature is introduced two different ways—by hydrophobic insertions into the membrane’s lipid bilayer, or by the presence of a scaffold made of curved BAR domain proteins. A recent paper sheds light on how these two membrane-remodeling mechanisms affects membrane fission. According to Boucrot and colleagues, the membrane insertion of a protein called epsin, which contains a hydrophobic ENTH domain, leads to membrane fission, while the curved BAR-domain scaffolds actually limit membrane fission. In addition, epsin is required for membrane fission of clathrin-coated vesicles. The electron micrograph above shows a clathrin-coated vesicle after depletion of all epsin proteins. Without epsin, vesicles are unable to bud from one another, creating a multi-headed structure.
Boucrot, E., Pick, A., Çamdere, G., Liska, N., Evergren, E., McMahon, H., & Kozlov, M. (2012). Membrane Fission Is Promoted by Insertion of Amphipathic Helices and Is Restricted by Crescent BAR Domains Cell, 149 (1), 124-136 DOI: 10.1016/j.cell.2012.01.047Copyright ©2012 Elsevier Ltd. All rights reserved.
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