E3 ubiquitin-protein ligase involved in postreplication repair of UV-damaged DNA. Postreplication repair functions in gap-filling of a daughter strand on replication of damaged DNA. Associates to the E2 ubiquitin conjugating enzyme UBE2B to form the UBE2B-RAD18 ubiquitin ligase complex involved in mono-ubiquitination of DNA-associated PCNA on 'Lys-164'. Has ssDNA binding activity.
Protein modification; protein ubiquitination.
Belongs to the RAD18 family. Contains 1 RING-type zinc finger. Contains 1 SAP domain. Contains 1 UBZ-type zinc finger.