RNA Exonuclease 2 Homolog (REXO2)

The deduced 205-amino acid protein has a calculated molecular mass of about 23.8 kD. The sequence shares about 50% identity with the E. coli Orn protein and contains 3 characteristic motifs, termed Exo I, II, and III, of the 3-prime-to-5-prime exonuclease superfamily. Four conserved negatively charged residues within the 3 Exo motifs are involved in positioning of the 2 divalent cations required for catalysis and phosphodiester bond cleavage. This variant appears to be a homolog of yeast Ynt20, which shows both RNAse and DNAse activity. Both SFN and SFN-alpha contain a consensus nuclear localization signal. Northern blot analysis revealed a 1-kb transcript expressed in all fetal and adult tissues tested, with highest levels in heart and relatively low levels in adult lymph nodes, brain, lung, liver, spleen, and thymus.