Enables aspartic-type endopeptidase activity. Involved in insulin catabolic process and insulin receptor recycling. Acts upstream of or within autophagosome assembly. Located in extracellular space and lysosome. Is active in endosome lumen. Is expressed in several structures, including central nervous system; extraembryonic component; eye; genitourinary system; and lung. Used to study neuronal ceroid lipofuscinosis 10. Human ortholog(s) of this gene implicated in Alzheimer's disease; breast cancer; and neuronal ceroid lipofuscinosis 10. Orthologous to human CTSD (cathepsin D).
