Figure 1

Modeling Transcriptional Regulation. (a) The S. pombe cell cycle transcriptional regulatory program. Shown are the phases of the cell cycle, known regulators and their regulatory interactions (arrows – activation; blunt arrows – repression). Figure adapted from [9], with some additions. (b) A qualitative molecular model of transcriptional regulation. mRNA encoding a transcription factor (TF, orange oval) is translated to protein (yellow oval). The protein is activated (pink oval) and induces the transcription of a target gene at a certain rate (G, blue oval). The final accumulation of G mRNA levels (G, orange oval) is determined by this transcription rate and by the rate of G's mRNA degradation. Each of the ovals is associated with a relevant quantity (TF mRNA level, TF protein level, activated TF protein level, transcription rate of the target gene G and mRNA level of G). A microarray experiment only measures the first and last of these quantities ("observed"), whereas the other quantities are not observed ("hidden"). The dashed oval encloses the closest quantities on this path between the TF and the target gene G. Our approach models the connection between these two variables.