Phase separating proteins and cellular switches

I will review experimental work on the behaviour in cells of a protein called Dishevelled. The unusual name derives from the fact that some mutations in Dishevelled cause fruit flies to develop with misaligned hairs on their bodies. The work has shown it apparently phase separating inside the cytosol of cells. Mutant variants of this protein that cannot phase separate, also cannot perform their biological function. This suggests that phase separation is required for the function of the protein. I will also introduce a simple model for phase separation inside the cell and show that its predictions are consistent with the experimental data. Finally, there is evidence of other proteins apparently phase separating inside cells. Cells may be exploiting the switch-like nature of phase separation, and/or its ability to dynamically create a compartment in the cytoplasm, for a number of different functions.