Responding to directional cues: a tale of two cells [biochemical signaling pathways]

The study of biochemical signaling pathways is of immense importance. Abnormalities in cell signaling have been linked to the development of many serious diseases. In this article, the author has presented two of the best-understood signaling pathways in eukaryotic cells and illustrated the similarities between traditional control engineering tasks, including step disturbance rejection and amplification. The illustrations have shown how directional sensing and polarization can be explained using models of the gradient sensing mechanism of Saccharomyces cerevisiae and Dictostelium discoideum. In particular, the author explains how negative feedback is used by Dictostelium discoideum cells to remain responsive to wide changes. The article also presents how Saccharomyces cerevisiae uses positive feedback loops to stabilize the polarization orientation.