The 2 human protamines are denoted PRM1 and PRM2. The histones are mostly displaced, and replaced by protamines (small, arginine-rich proteins). The testis-specific proteins that show the highest level of expression are protamines. In contrast to prokaryotes, NAGS in mammals is enhanced by arginine, along with protamines. Male protamines are replaced with histones and the male DNA is demethylated.