HTRA2 also known as Omi is a member of the serine protease family. HTRA2 plays a crucial role in cellular stress responses by degrading misfolded proteins, thereby preventing the accumulation of potentially toxic aggregates. HTRA2 is predominantly localized in the mitochondria and is involved in regulating apoptosis, making HTRA2 essential for maintaining cellular homeostasis. HTRA2 is expressed in various tissues, including the kidney, colon, and thyroid, and HTRA2 expression is tightly regulated; alterations in HTRA2 levels have been implicated in several diseases, including neurodegenerative disorders and cancer. HTRA2 exists in two polypeptide forms and features a modified PDZ domain that influences HtrA2 interactions with other proteins, such as the Mxi2 protein, which is not recognized by the alternatively spliced D-Omi form.