This family contains Prp8 domain IV, which adopts a RNase H like fold within its core structure but with little sequence similarity. Prp8, a spliceosome protein, interacts directly with the splice sites and branch regions of precursor-mRNAs and spliceosomal RNAs associated with catalysis of the two steps of splicing. Catalysis of RNA cleavage by RNase H-like proteins involves a two-metal mechanism in which adjacently-bound divalent magnesium ions promote hydrolysis by activation of a water nucleophile and stabilization of the transition-state. However, the Prp8 domain IV contains only one of the canonical metal-binding sites and the coordinating side chains are spatially conserved with respect to Mg2+-coordinating residues within the RNase H fold.
Jiyao W et al.(2023). "The conserved domain database in 2023.",