Research

In eukaryotic cells, organelles exchange materials in membranous vesicles in a process called intracellular membrane trafficking. To ensure proper sorting, a given membrane needs to be identified before assigned to transport machineries. The protein family, small GTPases, establish membrane identity on various organelles and vesicles. They act as the molecular switches and once activated, they are attached to the membrane and recruit the same molecular to the surrounding membranes. To quantitatively understand this complicated process in which diffusion plays a key role, synthetic model systems are being made to dissect how individual reaction affects the overall kinetics and dynamics.

During evolution, positive feedback often emerges in gene regulation and leads to a switch like response that allows activating certain genes only when the environmental stimuli reach a certain threshold. However, such feedback systems can also result in a phenomenon called cellular memory, or hysteresis. In this case, the cellular response to an environmental stimulus depends on whether the cell has been activated before: a previously activated cell stays activated and vice versa. Obviously, cellular memory slows down or even prevents proper response, which can cause adaptation disadvantage. A synthetic system is being established to study how such switching rates affect fitness and how switching rate evolves in a population under rapid and extreme environmental change.