Cathepsin E: An Aspartic Protease with Diverse Functions and Biomedical Implications

Aspartic peptidases are widely distributed among vertebrates, yeast, plants, fungi, bacteria, and viruses. Of these, the A1 family members, including cathepsin E and ß-secretase, are involved in specific and/or nonspecific degradation of proteins and peptides in intra- and/or extracellular spaces. In the last decade, cathepsin E and ß-secretase have received enormous interest because of their involvement in important biological processes and the close association of their abnormal expression and uncontrolled activity with human diseases. This review summarizes the current knowledge on biochemical properties and functions of cathepsin E and highlights the pathophysiological conditions caused by its deficiency.