RING-like Rtf2 domain, C2HC2-type, found in the replication termination factor 2 (Rtf2) protein family
The Rtf2 protein family includes a group of conserved proteins found in eukaryotes ranging from fission yeast to humans. The defining member of the family is Schizosaccharomyces pombe Rtf2 (SpRtf2), which is a proliferating cell nuclear antigen-interacting protein that functions as a key requirement for efficient replication termination at the site-specific replication barrier RTS1. It promotes termination at RTS1 by preventing replication restart. SpRtf2 contains a RING-like Rtf2 domain that is characterized by a C2HC2 motif similar to C3HC4 RING-HC finger motif known to bind two Zn2+ ions and mediate protein-protein interactions. The C2HC2 motif lacks three of the seven conserved cysteines of the C3HC4 motif, and forms only one functional Zn2+ ion-binding site. The RING-like Rtf2 domain in fission yeast is required to stabilize a paused DNA replication fork during imprinting at the mating type locus, possibly by facilitating sumoylation of PCNA. The family also includes Arabidopsis RTF2 (AtRTF2), an essential nuclear protein required for both normal embryo development and for proper expression of the GFP reporter gene. It plays a critical role in splicing the GFP pre-mRNA, and may also have a more transient regulatory role during the spliceosome cycle. The biological function of Rtf2 homologs found in eumetazoa remains unclear. They contain a variant C2HC2 motif where the middle conserved histidine has been replaced by cysteine.
Comment:The RING-like Rtf2 domain is characterized by a C2HC2 motif similar to C3HC4 RING-HC finger motif known to bind two Zn2+ ions and mediate protein-protein interactions. The C2HC2 motif lacks three of the seven conserved cysteines of the C3HC4 motif, and forms only one functional Zn2+ ion-binding site.
Comment:The RING-like Rtf2 domain found in eumetazoa Rtf2 homologs contains a variant C2HC2 motif where the middle conserved histidine has been replaced by cysteine.
Jiyao W et al.(2023). "The conserved domain database in 2023.",