![]() ![]() The shape of cell membranes is far from being a passive consequence of protein activity it is a key and actively modulated input to many biochemical processes. In the context of cell–cell junctions, membrane curvature assists in nucleating cadherin Concluding remarks Indeed, the capacity of cells to migrate in a coherent, directional manner is intricately linked to membrane shape changes. The signals generated coordinate biochemical activities, control the timing of discrete steps within the process, and enhance the robustness of the process. Through the mechanisms we have outlined above, membrane curvature acts as a signal source in diverse biological processes. Thus, the transport An integrated view: membrane curvature as a control mechanism to ensure robustness of complex processes This curvature-based lipid sorting slows movement of lipids even above the typical miscibility temperature of the lipid bilayer (Figure 4A). Membrane curvature can induce phase separation of lipids into distinct compartments consisting of ordered and disordered lipids. In addition to the effect on affinities described above, membrane curvature has been shown to affect the dynamic activities of both lipids and membrane-associated enzymes through various mechanisms. ![]() This curvature-sensitive filament recruitment is essential Consequences of membrane curvature for chemical kinetics In vivo, the bacterial actin-related protein MreB creates filaments that preferentially localize along the high mean curvature sides of an Escherichia coli cell of radius ~500 nm. In vitro, the Atg12–Atg5–Atg16L1 autophagy elongation complex is 100-fold enriched on high-curvature tubules (~20 nm radius) over flat membrane. Membranes of specific geometries drive the recruitment of specific proteins in vitro and in vivo (Figure 3A). Above some threshold concentration, however, amphiphysin induces membrane Equilibrium effects: membrane curvature changes protein affinity In reconstituted systems, the division is frequently a function of both protein concentration and membrane tension: at low membrane tension and protein concentrations, proteins such as amphiphysin sense membrane curvature by preferentially binding to higher-curvature areas over lower-curvature areas. The question of whether a protein induces or senses curvature is one that persists in cell biology (Figure 2A). At the same time, processes intrinsic to the Inducing versus sensing curvature: a difference of degrees For instance, invading cancer cells must press their plasma membranes forward to migrate, and in doing so bend their plasma membranes around obstacles including the extracellular matrix (ECM). A key parameter in human physiology is the ability of a cell to both produce and respond to 3D shape across vast length-scales. Mammalian cells are internally compartmentalized by curved membranes and exist in a 3D world that bends the plasma membrane. Section snippets Membrane curvature is generated by cellular surroundings or internal protein–membrane remodeling ![]()
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