Lysosomal 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 .
Subcellular locations: Lysosome, Melanosome
Identified by mass spectrometry in melanosome fractions from stage I to stage IV.
Detected in all tissues examined with highest levels in heart and placenta and relatively similar levels in other tissues.