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BP: Fachverband Biologische Physik

BP 8: Bioimaging and Biospectroscopy

BP 8.5: Vortrag

Montag, 22. März 2021, 15:20–15:40, BPb

Self-organization of endoplasmic reticulum exit sites — •Konstantin Speckner, Lorenz Stadler, and Matthias Weiss — Experimentalphysik 1, Universität Bayreuth

The endoplasmic reticulum (ER) is a highly dynamic organelle that pervades the entire cell and hosts a variety of vital processes. For example, the exchange of proteins with the secretory pathway occurs at specialized and long-lived membrane domains, called ER exit sites (ERES). In mammalian cells, ERES form protein assemblies that emerge as a lattice-like arrangement of dispersed droplets on the ER membrane. Although ERES were seen to diffuse on short timescales, they appear stationary on longer periods. Notably, their dynamics is different from the cytoskeleton-dependent, shivering motion of ER tubules. To gain insights into the self-organization of ERES patterns, we have studied biochemical perturbations on the morphology of the ER and analyzed the spatial arrangement of ERES by quantitative fluorescence imaging. As a result, we found a significantly changed patterns of ERES components when reducing the amount of curvature-inducing membrane proteins. In contrast, disrupting the ER network into fragments or affecting the cytoskeletons integrity had only mild effects on the ERES patterns. Our findings can be well explained by modelling ER junctions as diffusion barriers for the exchange of ERES protein constituents. Altogether, we provide evidence that the native ERES patterns are the result of a quenched fluctuation-driven two-dimensional demixing process.