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BP: Fachverband Biologische Physik
BP 24: Physics of Cells II
BP 24.9: Vortrag
Donnerstag, 17. März 2011, 12:30–12:45, ZEU 250
Spatial organization of the cell cytoplasm: Protein gradients and liquid-liquid phase separation in the C. elegans embryo — •Chiu Fan Lee1, Clifford P. Brangwynne2, Zdeněk Petrášek3, Jöbin Gharakhani1, Anthony A. Hyman2, and Frank Jülicher1 — 1Max Planck Institute for the Physics of Complex Systems, Dresden, Germany — 2Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany — 3Biotechnologisches Zentrum der TU Dresden, Dresden, Germany
During the asymmetric division of the one-cell stage embryo of the nematode C. elegans, germ line granules (P-granules) segregate and localize in the posterior half of the cell in order to be unequally distributed to the two daughter cells. Segregation occurs via a spatial gradient of supersaturation of P-granule components which nucleate in droplets on in the posterior side and dissolve in the anterior side. This supersaturation gradient is generated by a concentration gradient of the protein Mex-5. Using a combined experimental and theoretical approach, we show that the Mex-5 gradient is established by a modulation of the diffusivity of Mex-5 via reactions that occur at the cell cortex and within the cytoplasm. We propose that Mex-5 may control P-granule phase separation via its competitive RNA binding activity, by which the local Mex-5 concentration influences the saturation point of the phase transition that triggers P-granule formation.