  Numerous transcription factors self-assemble into different order oligomeric
species in a way that is actively regulated by the cell. Until now, no general
functional role has been identified for this widespread process. Here we
capture the effects of modulated self-assembly in gene expression with a novel
quantitative framework. We show that this mechanism provides precision and
flexibility, two seemingly antagonistic properties, to the sensing of diverse
cellular signals by systems that share common elements present in transcription
factors like p53, NF-kappaB, STATs, Oct, and RXR. Applied to the nuclear
hormone receptor RXR, this framework accurately reproduces a broad range of
classical, previously unexplained, sets of gene expression data and
corroborates the existence of a precise functional regime with flexible
properties that can be controlled both at a genome-wide scale and at the
individual promoter level.
