Figure 7: Models for the regulation of Pol η by mono-UBLylation.

(A) A schematic illustrating a previously proposed model for the interaction between Pol η and mono-ubiquitinated PCNA (16). The PIP box and nuclear localization signal (NLS) of Pol η were suggested to form an extended binding interface with PCNA, while the ubiquitin-binding zinc finger (UBZ) binds the mono-ubiquitin moiety (B) An AlphaFold 3 model of the Pol η C-terminus in complex with PCNA. This model was overlaid with the crystal structure of mono-ubiquitinated PCNA (PDB 3TBL) to position the ubiquitin group. AlphaFold was also used to model the UBZ-PCNA interaction. The orange surface of PCNA represents the universal binding site, which can be seen interacting with the Pol η PIP box. (C) A model of Pol η regulation by mono-ubiquitination and mono-NEDDylation.