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Organelles communicate thanks to flexible and polyspecific proteins
6 July 2021 @ 11 h 30 min – 12 h 30 min
Institut Curie, UMR168 CNRS, Paris
In eukaryotes, endoplasmic reticulum (ER) establishes direct contact with all other organelles. Within these contact zones, called membrane contact sites (MCS), protein complexes bridge membranes and ensure a specific function. There is not yet structure of protein complexes involved in MCS. The ER protein VAP-A (VAMP-associated protein A), present in ER-organelle MCS, is recognized by >100 partners including several cytoplasmic lipid transfer proteins. We designed an in vitro MCSs consisting of several complexes made with VAP-A (29 Kda) and OSBP (89 kDa) a cholesterol transporter and tethering two membranes. Thanks to the advances of cryo-tomography and subtomogram averaging, we obtained 3D model of MCS at nm resolution, showing that VAP is a flexible molecule that allows the concentration of different partners in specific areas of the ER. This provide insights on how proteins concentrated in a confined space can ensure their function.