| Abstract: |
| A response curve measures the output of a biological system at equilibrium against an input parameter, which could be a rate constant, the dose of a ligand, or the strength of an external signal. While often monotonic, a response curve that is biphasic serves as a mechanism against over-activation. For example, it has been observed that a T-cell`s response to antigen concentration is non-monotonic. It has been conjectured that an incoherent feedforward loop is necessary to explain biphasic response. In this talk, we establish necessary conditions for biphasic response for general non-linear systems. More precisely, we proved that either an incoherent feedforward loop, or a combination of positive and negative feedback loops, is necessary for biphasic response. |
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