UBA1 domain of Schizosaccharomyces pombe UV excision repair protein Rhp23p and its homologs
The subfamily contains several fungal multi-ubiquitin receptors, including Schizosaccharomyces pombe Rhp23p and Saccharomyces cerevisiae Rad23p, both of which are orthologs of human HR23A. They play roles in nucleotide excision repair (NER) and in cell cycle regulation. They also function as shuttle proteins transporting ubiquitinated substrates destined for degradation from the E3 ligase to the 26S proteasome. For instance, S. pombe Rhp23p forms a complex with Rhp41p to recognize photolesions and help initiate DNA repair, and it also protects ubiquitin chains against disassembly by deubiquitinating enzymes. Like human HR23A, members in this subfamily interact with the proteasome through their N-terminal ubiquitin-like domain (UBL), and with ubiquitin (Ub), or multi-ubiquitinated substrates, through their two ubiquitin-associated domains (UBA), termed internal UBA1 and C-terminal UBA2. In addition, they contain a xeroderma pigmentosum group C (XPC) protein-binding domain that might be necessary for its efficient NER function. This model corresponds to the UBA1 domain.
Jiyao W et al.(2023). "The conserved domain database in 2023.",