tripeptidyl-peptidase 1; TPP-1; cell growth-inhibiting gene 1 protein; lysosomal pepstatin-insensitive protease; LPIC; tripeptidyl aminopeptidase; tripeptidyl-peptidase I; TPP-I (TPP1, GIG1, UNQ267/PRO304)

Function

• lysosomal serine protease with tripeptidyl-peptidase 1 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 (putative)
• release of an N-terminal tripeptide from a polypeptide, but also has endopeptidase activity
• activated by autocatalytic proteolytical processing upon acidification

Cofactor: binds 1 Ca+2 per subunit

Structure

• monomer
• N-glycosylation
  • N-glycosylation is required for processing & activity
• belongs to the peptidase S53 family

Compartment

• lysosome, melanosome

Alternative splicing

named isoforms=2

Expression

• detected in all tissues examined
• highest levels in heart & placenta
• lower & relatively similar levels in other tissues

Pathology

• defects in TPP1 are the cause of neuronal ceroid lipofuscinosis type 2

Laboratory

• tripeptidyl peptidase 1 in dried blood spot
• tripeptidyl peptidase 1 in fibroblasts
• tripeptidyl peptidase 1 in leukocytes

More general terms

• aminopeptidase
• glycoprotein
• Ca+2 binding protein

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=1200
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:1200
• OMIM: https://mirror.omim.org/entry/204500
• OMIM: https://mirror.omim.org/entry/607998
• UniProt: http://www.uniprot.org/uniprot/O14773.html