Hersen P, McClean MN, Mahadevan L, Ramanathan S. 2008. Signal processing by the HOG MAP kinase pathway. Proceedings of the National Academy of Sciences of the United States of America. 105(20):7165-70. Pubmed: 18480263 DOI:10.1073/pnas.0710770105


Signaling pathways relay information about changes in the external environment so that cells can respond appropriately. How much information a pathway can carry depends on its bandwidth. We designed a microfluidic device to reliably change the environment of single cells over a range of frequencies. Using this device, we measured the bandwidth of the Saccharomyces cerevisiae signaling pathway that responds to high osmolarity. This prototypical pathway, the HOG pathway, is shown to act as a low-pass filter, integrating the signal when it changes rapidly and following it faithfully when it changes more slowly. We study the dependence of the pathway's bandwidth on its architecture. We measure previously unknown bounds on all of the in vivo reaction rates acting in this pathway. We find that the two-component Ssk1 branch of this pathway is capable of fast signal integration, whereas the kinase Ste11 branch is not. Our experimental techniques can be applied to other signaling pathways, allowing the measurement of their in vivo kinetics and the quantification of their information capacity.

Related Faculty

Photo of Sharad Ramanathan

Sharad Ramanathan studies how the dynamics of the underlying circuits allow cells and organisms to make decisions. To do so he brings together Biology with tools from Applied Math, Microscopy and Microfluidics.

Search Menu