Ribonuclease A8 (RNASE8)

As part of a large-scale human genome sequencing effort, Zhang et al. identified RNASE8. The deduced 154-amino acid protein has a signal peptide of 27 amino acids and contains 8 cysteines as well as the catalytic lysine and histidine residues typical of RNASE A superfamily members. RNASE8 is most similar to RNASE7 , sharing 78% identity, and shares 29% identity to RNASE5 (ANG). Northern blot analysis of 12 human tissues detected an approximately 1.0-kb transcript expressed exclusively in placenta.Zhang et al. demonstrated that recombinant RNASE8 has ribonucleolytic activity against yeast tRNA.By genomic sequence analysis, Zhang et al. mapped the RNASE8 gene to chromosome 14q11.2, where it is linked to 7 other RNase A superfamily genes and is closest to RNASE7, which is 15 kb downstream. The authors noted that the entire RNase A cluster spans 368 kb.