Modularity, Retroactivity, and Structural Identification

Abstract

Many reverse-engineering techniques in systems biology rely upon data on steady-state (or dynamic) perturbations - obtained from siRNA, gene knockdown or overexpression, kinase and phosphatase inhibitors, or other interventions in order to understand the interactions between different 'modules' in a network. This paper first reviews one popular such technique, introduced by the author and collaborators, and also discusses why conclusions drawn from its (mis-)use may be misleading due to 'retroactivity' (impedance or load) effects. A theoretical result characterizing stoichiometric-induced steady-state retroactivity effects is given for a class of biochemical networks.