Monday, October 9th, 11h30, Room 454 A, Condorcet Building.

Formation of the Golgi apparatus by protein self-assembly

Frédéric Pincet

Membrane biophysics

LPENS (Laboratoire de Physique de l’école normale supérieure).
Département de physique. ENS-PSL

We are in the midst of a revolution in our understanding of the internal organization of cells.  In the 1950s we learned that lipid bilayer-based membranes serve as containers (organelles) within the cytoplasm. Now we are learning that liquid-like “membrane-less” organelles i.e. without any container, self-assemble based on “liquid-liquid” phase separations. We propose the seemingly radical idea that, like their membrane-less counterparts, the membrane-bounded Golgi Apparatus cisternae are stabilized or even templated by analogous phase separations of their surface proteins, the golgins, into largely planar liquids. In this hypothesis, the Golgi self-organizes as a multi-layered series of adherent phases of golgins. In this seminar, I will present how we are testing this hypothesis in vitro and show that golgins do phase separate in 2D on model membranes. Quantitative analysis and modeling of the condensates suggest that the structures are maintained by weak intermolecular interactions, within and between cisternae.

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