Cathepsin C
Encyclopedia
Cathepsin C also known as dipeptidyl peptidase I (DPP-I) is a lysosomal
exo-cysteine protease
belonging to the peptidase C1 family. In humans, it is encoded by the CTSC gene
.
s in immune/inflammatory cells.
Cathepsin C catalyses excision of dipeptides from the N-terminus of protein and peptide substrates, except if (i) the amino group of the N-terminus is blocked, (ii) the site of cleavage is on either side of a proline residue, (iii) the N-terminal residue is lysine or arginine, or (iv) the structure of the peptide or protein prevents further digestion from the N-terminus.
and a number of other cathepsins including cathepsins, B
, H, K
, L
, and S
.
The translated prepro-cathepsin C is processed into the mature form by at least four cleavages of the polypeptide chain. The signal peptide is removed during translocation or secretion of the pro-enzyme (pro-cathepsin C) and a large N-terminal proregion fragment (also known as the exclusion domain), which is retained in the mature enzyme, is separated from the catalytic domain by excision of a minor C-terminal part of the pro-region, called the activation peptide. A heavy chain of about 164 residues and a light chain of about 69 residues are generated by cleavage of the catalytic domain.
Unlike the other members of the papain
family, mature cathepsin C consists of four subunits, each composed of the N-terminal proregion fragment, the heavy chain and the light chain. Both the pro-region fragment and the heavy chain are glycosylated.
, an autosomal recessive disorder characterized by palmoplantar keratosis
and periodontitis.
Cathepsin C functions as a key enzyme in the activation of granule serine peptidases in inflammatory cells, such as elastase and cathepsin G in neutrophils cells and chymase and tryptase in mast cells. In many inflammatory diseases, such as Rheumatoid Arthritis, Chronic Obstructive Pulmonary Disease (COPD), Inflammatory Bowel Disease, Asthma, Sepsis and Cystic Fibrosis, a significant part of the pathogenesis is caused by increased activity of some of these inflammatory proteases. Once activated by cathepsin C, the proteases are capable of degrading various extracellular matrix components, which can lead to tissue damage and chronic inflammation.
Lysosome
thumb|350px|Schematic of typical animal cell, showing subcellular components. [[Organelle]]s: [[nucleoli]] [[cell nucleus|nucleus]] [[ribosomes]] [[vesicle |vesicle]] rough [[endoplasmic reticulum]]...
exo-cysteine protease
Cysteine protease
Proteases are enzymes that degrade polypeptides. Cysteine proteases have a common catalytic mechanism that involves a nucleophilic cysteine thiol in a catalytic dyad. The first step is deprotonation of a thiol in the enzyme's active site by an adjacent amino acid with a basic side chain, usually a...
belonging to the peptidase C1 family. In humans, it is encoded by the CTSC gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
.
Function
Cathepsin C appears to be a central coordinator for activation of many serine proteaseSerine protease
Serine proteases are enzymes that cleave peptide bonds in proteins, in which serine serves as the nucleophilic amino acid at the active site.They are found ubiquitously in both eukaryotes and prokaryotes...
s in immune/inflammatory cells.
Cathepsin C catalyses excision of dipeptides from the N-terminus of protein and peptide substrates, except if (i) the amino group of the N-terminus is blocked, (ii) the site of cleavage is on either side of a proline residue, (iii) the N-terminal residue is lysine or arginine, or (iv) the structure of the peptide or protein prevents further digestion from the N-terminus.
Structure
The cDNAs encoding rat, human, murine, bovine, dog and two Schistosome cathepsin Cs have been cloned and sequenced and show that the enzyme is highly conserved. The human and rat cathepsin C cDNAs encode precursors (prepro-cathepsin C) comprising signal peptides of 24 residues, pro-regions of 205 (rat cathepsin C) or 206 (human cathepsin C) residues and catalytic domains of 233 residues which contain the catalytic residues and are 30-40% identical to the mature amino acid sequences of papainPapain
Papain, also known as papaya proteinase I, is a cysteine protease enzyme present in papaya and mountain papaya .-Papain family:...
and a number of other cathepsins including cathepsins, B
Cathepsin B
Cathepsin B is an enzymatic protein belonging to the peptidase families. In humans, it is coded by the CTSB gene.- Function :...
, H, K
Cathepsin K
Cathepsin K, abbreviated CTSK, is an enzyme which in humans is encoded by the CTSK gene.- Function :The protein encoded by this gene is a lysosomal cysteine protease involved in bone remodeling and resorption...
, L
Cathepsin L
Cathepsin L can refer to:* Cathepsin L1, previously called cathepsin L* Cathepsin L2 or cathepsin V...
, and S
Cathepsin S
Cathepsin S, also known as CTSS, is a protein which in humans is encoded by the CTSS gene.The protein encoded by this gene, a member of the peptidase C1 family, is a lysosomal cysteine protease that may participate in the degradation of antigenic proteins to peptides for presentation on MHC class...
.
The translated prepro-cathepsin C is processed into the mature form by at least four cleavages of the polypeptide chain. The signal peptide is removed during translocation or secretion of the pro-enzyme (pro-cathepsin C) and a large N-terminal proregion fragment (also known as the exclusion domain), which is retained in the mature enzyme, is separated from the catalytic domain by excision of a minor C-terminal part of the pro-region, called the activation peptide. A heavy chain of about 164 residues and a light chain of about 69 residues are generated by cleavage of the catalytic domain.
Unlike the other members of the papain
Papain
Papain, also known as papaya proteinase I, is a cysteine protease enzyme present in papaya and mountain papaya .-Papain family:...
family, mature cathepsin C consists of four subunits, each composed of the N-terminal proregion fragment, the heavy chain and the light chain. Both the pro-region fragment and the heavy chain are glycosylated.
Clinical significance
Defects in the encoded protein have been shown to be a cause of Papillon-Lefevre diseasePapillon-Lefevre disease
Papillon–Lefèvre syndrome , also known as palmoplantar keratoderma with periodontitis, is an autosomal recessive genetic disorder caused by a deficiency in cathepsin C.-Characteristics:...
, an autosomal recessive disorder characterized by palmoplantar keratosis
Keratosis
Keratosis is a growth of keratin on the skin. More specifically, it can refer to:* actinic keratosis * hydrocarbon keratosis* keratosis pilaris , also known as * seborrheic keratosis-See also:...
and periodontitis.
Cathepsin C functions as a key enzyme in the activation of granule serine peptidases in inflammatory cells, such as elastase and cathepsin G in neutrophils cells and chymase and tryptase in mast cells. In many inflammatory diseases, such as Rheumatoid Arthritis, Chronic Obstructive Pulmonary Disease (COPD), Inflammatory Bowel Disease, Asthma, Sepsis and Cystic Fibrosis, a significant part of the pathogenesis is caused by increased activity of some of these inflammatory proteases. Once activated by cathepsin C, the proteases are capable of degrading various extracellular matrix components, which can lead to tissue damage and chronic inflammation.
External links
- The MEROPSMeropsMerops may refer to:* Merops , a genus of bee-eaters.* MEROPS, an on-line database for peptidases.It may also refer to several figures from Greek mythology:* King of Ethiopia, husband of Clymene, who lay with Helios and bore Phaethon...
online database for peptidases and their inhibitors: C01.070