Figure 5: The FUSE–FBP–FIR–TFIIH Governor for c-MYC transcription.(A) In the absence of appropriate growth signals, c-MYC is not transcribed, and the FUSE element is double-stranded and nucleosome-bound. (B) Upon induction, MYC is transcribed at a low level and as a result the FUSE element transitions to a partially single-stranded state. (C) Single-stranded FUSE is bound by FBP, which then contacts TFIIH (IIH), forming a localized loop in the promoter (D). (E) FBP stimulates transcription, the effect of which is to induce supercoiling in the loop, which in turn fully melts the FUSE element. (F). Melting of FUSE leads to loss of FBP and recruitment of the FIR repressor, which inhibits transcription, leading to a reduction in localized torsional stress, returning the promoter to the basal state (B). Only the P2 promoter is shown for clarity. “GTF” refers to the general transcription factors (including RNA polymerase II).