Aspartic protease is a type of protease with aspartic acid residues at its active center, including members like pepsin and HIV protease. Their structure typically features two symmetrical aspartic acid residues, responsible for catalyzing hydrolysis reactions. They are located variably in cells or tissues, involved in numerous biological reactions and signaling pathways, such as digestion, immune response, and virus replication. Gene expression is specific, showing significant differences across tissues or developmental stages. Mutations may lead to diseases, such as hereditary brain diseases.