This entry includes Rad18 from eukaryotes. Rad18 is a E3 ubiquitin ligase required for postreplication repair []. In budding yeast, Rad18 forms a heterodimer with Rad6 to monoubiquitinate PCNA at a highly conserved lysine, 'Lys-164' []. In humans, Rad18 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' [].
During DNA replication, lesion bypass is an important cellular response to unrepaired damage in the genome. In the yeastSaccharomyces cerevisiae (Baker's yeast), Rad6 and Rad18 are required for both the error-free and error-prone lesion bypass mechanisms. The Rad18 gene encodes a RING-finger protein with single-stranded DNA binding activity that interacts with theubiquitin-conjugating enzyme Rad6. This entry represents the Rad8 from fungi.
This domain is found in the Werner helicase-interacting protein 1 present in Homo sapiens. The domain is a zinc finger responsible and has a zinc-coordinating B-B-A fold. WRNIP1 UBZ binds ubiquitin in a similar manner to Rad18 UBZ [].
The ubiquitin-binding zinc finger (UBZ) is a type of zinc-coordinating β-β-α fold domain found mainly in proteins involved in DNA repair and transcriptional regulation. UBZ domains coordinate a zinc ion with cysteine or histidine residues; depending on their amino acid sequence, UBZ domains are classified into several families [, ]. Type 1 UBZs are CCHH-type zinc fingers found in tandem UBZ domains of TAX1-binding protein 1 (TAX1BP1) [, , ], type 2 UBZs are CCHC-type zinc fingers found in FAAP20 which is a subunit of the Fanconi anemia (FA) core complex [, ], type 3 UBZs are CCHH-type zinc fingers found only in the Y-family translesion polymerase eta [, , ], and type 4 UBZs are CCHC-type zinc fingers found in Y-family translesion polymerase kappa, Werner helicase-interacting protein 1 (WRNIP1), and Rad18 [, , ]. The UBZ domain consists of two short antiparallel β-strands followed by one α-helix. The α-helix packs against the β-strands with a zinc ion sandwiched between the α-helix and the β-strands. The zinc ion is coordinated by two cysteines located on the fingertip formed by the β-strands and two histidines [, ]or one histidine and one cysteine []on the α-helix [].This entry represents type 4 UBZ found in RAD18. The domain is a potential zinc finger for nucleic acid binding and a putative nucleotide binding sequence []. Human RAD18 accumulates very rapidly and remains for a long period of time at sites of different types of DNA damage, and is required of DNA. RAD18 appears to respond to DNA damage in two distinct ways: replication-dependent and replication-independent. The RAD18-type zinc finger located in the middle of RAD18 is responsible for the replication-independent accumulation of RAD18 following DNA damage, while a second zinc finger, SAP-type, is responsible for replication-dependent accumulation [].
This entry represents the FAM178 family, whose members are metazoan proteins and include FAM178A and FAM178B. The human FAM178A protein has been shown to be widely expressed []and is phosphorylated upon DNA damage, probably by ATM (ataxia telangiectasia mutated) or ATR (ATM and Rad3-related) [, ].FAM178A, also known as SLF2 (SMC5-SMC6 complex localization factor 2), forms a complex with RAD18 and SLF1, and together they define a pathway that suppresses genome instability by recruiting the SMC5/6 cohesion complex to DNA lesions [, ].
The ubiquitin-binding zinc finger (UBZ) is a type of zinc-coordinating β-β-α fold domain found mainly in proteins involved in DNA repair and transcriptional regulation. UBZ domains coordinate a zinc ion with cysteine or histidine residues; depending on their amino acid sequence, UBZ domains are classified into several families [, ]. Type 1 UBZs are CCHH-type zinc fingers found in tandem UBZ domains of TAX1-binding protein 1 (TAX1BP1) [, , ], type 2 UBZs are CCHC-type zinc fingers found in FAAP20 which is a subunit of the Fanconi anemia (FA) core complex [, ], type 3 UBZs are CCHH-type zinc fingers found only in the Y-family translesion polymerase eta [, , ], and type 4 UBZs are CCHC-type zinc fingers found in Y-family translesion polymerase kappa, Werner helicase-interacting protein 1 (WRNIP1), and Rad18 [, , ]. The UBZ domain consists of two short antiparallel β-strands followed by one α-helix. The α-helix packs against the β-strands with a zinc ion sandwiched between the α-helix and the β-strands. The zinc ion is coordinated by two cysteines located on the fingertip formed by the β-strands and two histidines [, ]or one histidine and one cysteine []on the α-helix [].This domain is the type 2 UBZ found in Fanconi anemia-associated protein of 20kDa (FAAP20) [, , , ].
The ubiquitin-binding zinc finger (UBZ) is a type of zinc-coordinating β-β-α fold domain found mainly in proteins involved in DNA repair and transcriptional regulation. UBZ domains coordinate a zinc ion with cysteine or histidine residues; depending on their amino acid sequence, UBZ domains are classified into several families [, ]. Type 1 UBZs are CCHH-type zinc fingers found in tandem UBZ domains of TAX1-binding protein 1 (TAX1BP1) [, , ], type 2 UBZs are CCHC-type zinc fingers found in FAAP20 which is a subunit of the Fanconi anemia (FA) core complex [, ], type 3 UBZs are CCHH-type zinc fingers found only in the Y-family translesion polymerase eta [, , ], and type 4 UBZs are CCHC-type zinc fingers found in Y-family translesion polymerase kappa, Werner helicase-interacting protein 1 (WRNIP1), and Rad18 [, , ]. The UBZ domain consists of two short antiparallel β-strands followed by one α-helix. The α-helix packs against the β-strands with a zinc ion sandwiched between the α-helix and the β-strands. The zinc ion is coordinated by two cysteines located on the fingertip formed by the β-strands and two histidines [, ]or one histidine and one cysteine []on the α-helix [].This entry represents type 3 UBZ found in DNA polymerase eta (). It is important in the recruitment of the polymerase to the stalled replication machinery in translesion synthesis. The UBZ domain adopts a classical C2H2 zinc-finger structure characterized by a β-β-α fold [].
The ubiquitin-binding zinc finger (UBZ) is a type of zinc-coordinating β-β-α fold domain found mainly in proteins involved in DNA repair and transcriptional regulation. UBZ domains coordinate a zinc ion with cysteine or histidine residues; depending on their amino acid sequence, UBZ domains are classified into several families [, ]. Type 1 UBZs are CCHH-type zinc fingers found in tandem UBZ domains of TAX1-binding protein 1 (TAX1BP1) [, , ], type 2 UBZs are CCHC-type zinc fingers found in FAAP20 which is a subunit of the Fanconi anemia (FA) core complex [, ], type 3 UBZs are CCHH-type zinc fingers found only in the Y-family translesion polymerase eta [, , ], and type 4UBZs are CCHC-type zinc fingers found in Y-family translesion polymerase kappa, Werner helicase-interacting protein 1 (WRNIP1), and Rad18 [, , ]. The UBZ domain consists of two short antiparallel β-strands followed by one α-helix. The α-helix packs against the β-strands with a zinc ion sandwiched between the α-helix and the β-strands. The zinc ion is coordinated by two cysteines located on the fingertip formed by the β-strands and two histidines [, ]or one histidine and one cysteine []on the α-helix [].This entry represents the UBZ1 type zinc finger domain found in calcium-binding and coiled-coil domain 1/2 (CALCOCO1/2), tax-binding protein 1 and protein spindle-F.This domain is a typical C2H2-type zinc finger which specifically recognizes mono-ubiquitin or poly-ubiquitin chain. The overall ubiquitin-binding mode utilizes the C-terminal α-helix to interact with the solvent-exposed surface of the central β-sheet of ubiquitin, similar to that observed in the RABGEF1/Rabex-5 or POLN/Pol-eta zinc finger [].CALCOCO2 (also known as NDP25) is an ubiquitin-binding autophagy receptor involved in the selective autophagic degradation of invading pathogens []. Tax binding protein 1 is a ubiquitin binding protein []and protein spindle-F plays a role in oocyte axis determination and microtubule organization during oogenesis in Drosophila [, ].
