title: [Tripeptidyl-peptidase I--distribution, biogenesis, and mechanisms of activation].
abstract: Tripeptidyl-peptidase I (TPPI) is an acidic lysosomal peptidase that removes tripeptides from an unmodified N-terminus of small proteins and polypeptides. In humans, TPP I constitutes an integral part of the lysosomal proteolytic apparatus, which, includes numerous hydrolytic enzymes, mostly cysteine proteases (cathepsin B, C, H, K, L, and others), but also serine (cathepsin A) and aspartic (cathepsin D) proteases. The combination of endo- and exopeptidase activities of these enzymes allows for efficient digestion of the diverse proteins transported to the lysosomes, releasing free amino acids and dipeptides that are transported back to the cytoplasm and reused according to the metabolic needs of the cell. The role of TPP I in normal lysosome functioning is underscored by the genetic association of the enzyme with one form of a group of the developmental neurodegenerative disorders of childhood--the neuronal ceroid lipofuscinoses (NCLs). The scope of this article is to review the most recent data, mostly from author's laboratory, on the biology and pathology of TPP I. NCLs are also shortly reviewed with the special emphasis on CLN2 form resulting from mutations in TPP I gene.
authors.affiliation: Department of Developmental Neurobiology, NYS Institute for Basic Research, 1050 Forest Hill Road, Staten Island, NY 10314, USA. adamgolabek@yahoo.com
authors.forename: Adam A
authors.initials: AA
authors.lastname: Gołabek
mesh_terms: D000626:Aminopeptidases; D000818:Animals; D001921:Brain / Q000201:enzymology / Q000503:physiopathology; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D010450:Endopeptidases / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007223:Infant; D020140:Lysosomal Storage Diseases, Nervous System / Q000201:enzymology / Q000235:genetics; D008247:Lysosomes / Q000378:metabolism*; D009154:Mutation; D009472:Neuronal Ceroid-Lipofuscinoses / Q000201:enzymology*; D001678:Organelle Biogenesis; D011480:Protease Inhibitors / Q000494:pharmacology; D057057:Serine Proteases; D013347:Subcellular Fractions / Q000201:enzymology; D000091346:Tripeptidyl-Peptidase 1
chemical_list: D011480:Protease Inhibitors; D000091346:Tripeptidyl-Peptidase 1; D010450:Endopeptidases; D057057:Serine Proteases; D000626:Aminopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C000717267:TPP1 protein, human