The CSP mapping showed FAAP20 has distinct binding surfaces for ubiquitin and Rev1.
FAAP20-UBZ4 interacts with ubiquitin through the C-terminal 伪-helix and tail.
UBZ4 bound to ubiquitin interacts with Rev1-BRCT through the same C-terminal tail.
We suggest a mechanism by which FAAP20 recognizes Rev1 during ICL repair.