Has a strict specificity for hydrolysis of asparaginyl bonds. Can also cleave aspartyl bonds slowly, especially under acidic conditions. May be involved in the processing of proteins for MHC class II antigen presentation in the lysosomal/endosomal system. Required for normal lysosomal protein degradation in renal proximal tubules. Required for normal degradation of internalized EGFR. Plays a role in the regulation of cell proliferation via its role in EGFR degradation. Hydrolysis of proteins and small molecule substrates at -Asn-|-Xaa- bonds. Inhibited by cystatin-C. Optimum pH is 6. May interact with integrins (By similarity). Monomer after autocatalytic processing. Homodimer before autocatalytic removal of the propeptide. Detected in kidney proximal tubules (at protein level). Ubiquitous. Particularly abundant in kidney and placenta. In the zymogen form, the uncleaved propeptide blocks access to the active site. Glycosylated. Activated by autocatalytic processing at pH 4. Young mice initially display no obvious phenotype, but fail to gain weight normally. Mutant mice display pale kidneys with abnormal proliferation of proximal tubule cells, proximal tubule hyperplasia and develop kidney interstitium fibrosis. After 6 months, mutant mice display a decreased glomerular filtration rate, increased plasma creatinine levels and proteinuria. Glomerular lysosomes do not show a generalized defect in protein catabolism. Instead they show defects in the degradation of a set of target proteins, including EGFR. Belongs to the peptidase C13 family.