NN8-4AG, or SMYD family member 5, is a human gene encoded by SMYD5. It may also be known as: SET and MYND domain-containing protein 5; Retinoic acid-induced protein 15; Protein NN8-4AG; SET and MYND domain-containing protein 5 ; RAI15; RRG1; ZMYND23. The encoded protein is an enzyme with an amino acid length of 418 and a mass of 47.3 kDa. Other isoforms may exist. NN8-4AG is a member of the Class V-like SAM-binding methyltransferase superfamily. Homologs of this gene exist in other organisms, including: Mouse, Rat, Zebrafish, Frog, Chicken.