HTRA4 encodes the human gene, HtrA serine peptidase 4. It may also be known as: Serine protease HTRA4; High-temperature requirement factor A4; Serine protease HTRA4 . The encoded protein is an enzyme with an amino acid length of 476 and a mass of 51.0 kDa. HTRA4 is a member of the Peptidase S1C family. Homologs of this gene exist in other organisms, including: Mouse, Rat, Zebrafish, Frog.