Has a strict specificity for hydrolysis of asparaginyl bonds (PubMed:23776206). Can also cleave aspartyl bonds slowly, especially under acidic conditions (PubMed:23776206). Involved in the processing of proteins for MHC class II antigen presentation in the lysosomal/endosomal system (PubMed:9872320). Also involved in MHC class I antigen presentation in cross-presenting dendritic cells by mediating cleavage and maturation of Perforin-2 (MPEG1), thereby promoting antigen translocation in the cytosol (By similarity). Required for normal lysosomal protein degradation in renal proximal tubules (By similarity). Required for normal degradation of internalized EGFR (By similarity). Plays a role in the regulation of cell proliferation via its role in EGFR degradation (By similarity).