Cystatin A is a type of protein that belongs to the cystatin family, which plays a crucial role in regulating enzymes called cysteine proteases. These enzymes are involved in various biological processes, including protein degradation and immune responses. Cystatin A is primarily found in human tissues, particularly in the skin and mucosal surfaces. This protein is important for maintaining the balance of protease activity in the body, helping to protect tissues from damage. Abnormal levels of Cystatin A have been linked to certain diseases, including cancer and neurodegenerative disorders, highlighting its potential role in health and disease management.