Exonuclease 1 is a human gene encoded by the symbol, EXO1. It may also be known as: hExo1; Exonuclease I; hExoI; rad2 nuclease family member, homolog of S. cerevisiae exonuclease 1; HEX1. The encoded protein is an enzyme with an amino acid length of 846 and a mass of 94.1 kDa. Other isoforms may exist. Exonuclease 1 is a member of the XPG/RAD2 endonuclease family, EXO1 subfamily. Homologs of this gene exist in other organisms, including: Mouse, Yeast, Rat, Zebrafish, Frog, Chicken.