InterPro domain: IPR037056

This entry represents the N-terminal domain superfamily of RNase HI, which has a 3-layer alpha/beta/alpha structure [ 1 ]. This domain is lacking in retroviral and prokaryotic enzymes, but shows a striking structural similarity to the ribosomal protein L9 N-terminal domain, and may function as a regulatory RNA-binding module. However, the topology of this domain differs from structures of known RNA binding domains such as the double-stranded RNA binding domain (dsRBD), the hnRNP K homology (KH) domain and the RNP motif. Eukaryotic RNases HI possess either one or two copies of this small N-terminal domain, in addition to the well-conserved catalytic RNase H domain. RNase HI belongs to the family of ribonuclease H enzymes that recognise RNA:DNA hybrids and degrade the RNA component.

1. NMR structure of the N-terminal domain of Saccharomyces cerevisiae RNase HI reveals a fold with a strong resemblance to the N-terminal domain of ribosomal protein L9. J. Mol. Biol. 291, 661-9