Fig. 4.

PCNA^S228I alters PCNA function via structural changes at the IDCL. A) Apo structure of PCNA^S228I (5MOM) shown in blue overlayed on apo PCNA^WT[43] structure in orange. The mutated I228 residues are shown as spheres. Top left inset zoomed area shows the rotation of Tyr133, propagating along the IDCL. Bottom left inset zoom shows K164 and surrounding structural environment unchanged. Right panel shows the rotated view of the IDCL region highlighted in B, C, D below. B) Magnified view of the IDCL region of a single monomer of PCNA^S228I colour coded according to the heat map of the rmsd between PCNA^S228I (5MOM) and PCNA^WT (1VYM). C) As B, but with residues found at the interface between PCNA^WT and the p21 pip box (based on 4RJF) coloured in red. D) As C, but for the Fen1 PIP box (based on 4RJF), coloured in magenta. E) PARD affected and control lymphoblasts were treated with the indicated doses of UVC and harvested after 7 h. Western blot shows induction of mono-ubiquitinated PCNA^WT and PCNA^S228I.