FunctionLysosomal serine protease with tripeptidyl-peptidase I activity. May act as a non-specific lysosomal peptidase which generates tripeptides from the breakdown products produced by lysosomal proteinases. Requires substrates with an unsubstituted N-terminus.
Tissue specificityDetected in all tissues examined with highest levels in heart and placenta and relatively similar levels in other tissues.
Involvement in diseaseDefects in TPP1 are the cause of neuronal ceroid lipofuscinosis type 2 (CLN2) [MIM:204500]. A form of neuronal ceroid lipofuscinosis. Neuronal ceroid lipofuscinoses are progressive neurodegenerative, lysosomal storage diseases characterized by intracellular accumulation of autofluorescent liposomal material, and clinically by seizures, dementia, visual loss, and/or cerebral atrophy. The lipopigment pattern seen most often in CLN2 consists of curvilinear profiles.
Sequence similaritiesBelongs to the peptidase S53 family.
Post-translational modificationsActivated by autocatalytic proteolytical processing upon acidification. N-glycosylation is required for processing and activity.
Cellular localizationLysosome. Melanosome. Identified by mass spectrometry in melanosome fractions from stage I to stage IV.