How membrane shape affects tetraspanin protein location

What is it about?

Various physiological processes involve protein-driven shaping and remodelling of membranes. Uncovering the mechanisms leading to membrane remodelling is, therefore, essential for understanding biological processes such as fertilization, as well as to allow intervention in such processes when needed. Multiple membrane remodelling processes are associated with proteins from the tetraspanin family by yet unknown mechanisms. In particular, tetrasapnin4 promotes the formation of cellular organelles called migrasomes which mediate cell-cell communication, and CD9 is indispensable for the process of fertilization. Here we discover that these proteins are curvature sensors with a preference for positive membrane curvature. As the transmembrane region of tetraspanins is highly conserved, the entire tetraspanin family might sense membrane curvature, and by this mediate tetraspanin functions.

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Photo by Greyson Joralemon on Unsplash

Photo by Greyson Joralemon on Unsplash

Why is it important?

Our biomimetic system with a big vesicle with a small tether is similar to two very important physiological scenarios: one is a cell with thin tubes called retraction fibers, that form during cell migration. Another is egg cells that have a ‘’hairy’’ side covered with membrane tubes, where fusion with sperm takes place! Our new findings can thus help better understand two biological processes: the formation of vesicles called migrasomes, that form at the retraction fibers of migrating cells, and fertilization which involves fusion and necessitates the membrane tubes that form thanks to tetraspanins.

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