Fig. 7: Overview of the TCR mechanism, possible defects, and resulting outcomes.
From: Hierarchical mechanisms control the clearance of DNA lesion–stalled RNA polymerase II
Model depicting the TCR mechanism when fully functional in blue (left), defects that may occur (middle, red), and their resulting outcomes (right, orange/green). Damage-stalled RNAPII is only cleared by XPD helicase under conditions of proficient TFIIH recruitment, positioning, and activity stimulation, allowing repair of the lesion. Any impairment of TFIIH function downstream of RNAPII ubiquitylation by CSB and CSA function leads to VCP-dependent clearance of damage-stalled RNAPII, without repair of the damage. Defects in CSB and CSA prevent any ubiquitylation of damage-stalled RNAPII, thus prohibiting both clearance pathways.
