ABSTRACT

Signaling pathways are instumental for gene transcription, through their action on transcription-controlling proteins, the so-called transcription factors (TF); see, e.g., [120]. TF interact with regulatory DNA motifs called promoter, enhancer or silencer sequences. Transcription is divided into three main phases: initiation, elongation and termination; we will present models describing the first phase. In eukaryotic cells, multiprotein complexes are formed; they are composed of RNA polymerase II and six general transcription factors. These TF are not gene specific and can thus be used for various genes. The activity of RNA polymerase, and of the general and gene-specific TF are controlled by signaling cascades, which are themselves activated by external stimuli. The DNA sequences of promoters and enhancers are composed of several distinct binding sites where gene specific transcription factors can bind, and thus enhance (positive regulation) or prevent (inhibition) transcription.