A protein stabilization system is a type of post-transcriptional processing that ubiquitously exists in various types of cells, and it plays a major role in stabilizing the three-dimensional conformation of a translated protein. It comprises a series of activation-deactivation reactions coupled with nucleocytoplasmic shuttling, and it is described by a four-dimensional nonlinear ordinary differential equation based on chemical kinetics. This study shows that this system can variously function as two types of integral controllers, low-pass filter, and integrator depending on the combination of the statuses of cytoplasmic and nucleus enzymes that mediate its reaction rates. This indicates that the system is multifunctional, where these statuses are controlled by the peripheral system around the stabilization system. In particular, because realizing an integral controller for regulating the concentration of a particular molecule to a desired level in biochemical reactions is theoretically and technically important in molecular robotics, the author demonstrates some numerical simulation results regarding integral control.
2015 The Society of Instrument and Control Engineers