Model genetic circuits encoding autoregulatory transcription factors.

Multiple steady-state levels of autoregulatory transcription factors are capable of specifying alternative heritable phenotypes of a cell or an organism. Switching among steady states can result in long-term phenotypic change. In this paper, six model genetic circuits are presented, each encoding a set of autoregulatory transcription factors. The steady-state rate equations for each genetic circuit are formulated and solved to determine conditions under which multiple steady states exist. Each steady state of the genetic circuit constitutes an alternative heritable phenotype resulting from a single genotype.