Lysosomal enzyme trafficking factor

Required for mannose-6-phosphate-dependent trafficking of lysosomal enzymes. LYSET bridges GlcNAc-1-phosphate transferase (GNPTAB), to the membrane-bound transcription factor site-1 protease (MBTPS1), thus allowing proteolytic activation of the GNPTAB. GNPTAB is involved in the regulation of M6P-dependent Golgi-to-lysosome trafficking of lysosomal enzymes. LYSET is thus an essential factor for maturation and delivery of lysosomal hydrolases.; (Microbial infection) Essential for infection by muliple viruses, including SARS-CoV-2, that utilize activated cathepsins for entry after M6P-dependent lysosomal transport.