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Cathepsins
Cathepsins (Ancient Greek ''kata-'' "down" and ''hepsein'' "boil"; abbreviated CTS) are proteases (enzymes that degrade proteins) found in all animals as well as other organisms. There are approximately a dozen members of this family, which are distinguished by their structure, catalytic mechanism, and which proteins they cleave. Most of the members become activated at the low pH found in lysosomes. Thus, the activity of this family lies almost entirely within those organelles. There are, however, exceptions such as cathepsin K, which works extracellularly after secretion by osteoclasts in bone resorption. Cathepsins have a vital role in mammalian cellular turnover. Classification * Cathepsin A (serine protease) * Cathepsin B (cysteine protease) * Cathepsin C (cysteine protease) * Cathepsin D (aspartyl protease) * Cathepsin E (aspartyl protease) * Cathepsin F (cysteine proteinase) * Cathepsin G (serine protease) * Cathepsin H (cysteine protease) * Cathepsin K (cysteine proteas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cysteine Cathepsin
Papain-like proteases (or papain-like (cysteine) peptidases; abbreviated PLP or PLCP) are a large protein family of cysteine protease enzymes that share protein structure, structural and catalytic mechanism, enzymatic properties with the group's namesake member, papain. They are found in all domains of life. In animals, the group is often known as cysteine cathepsins or, in older literature, lysosomal peptidases. In the MEROPS protease enzyme classification system, papain-like proteases form Clan CA. Papain-like proteases share a common catalytic dyad active site featuring a cysteine amino acid residue that acts as a nucleophile. The human genome encodes eleven cysteine cathepsins which have a broad range of physiological functions. In some parasites papain-like proteases have roles in host (biology), host invasion, such as cruzipain from ''Trypanosoma cruzi''. In plants, they are involved in host defense and in development. Studies of papain-like proteases from prokaryotes have la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathepsin L1
Cathepsin L1 is a protein that in humans is encoded by the ''CTSL1'' gene. The protein is a cysteine cathepsin, a lysosome, lysosomal cysteine protease that plays a major role in intracellular protein catabolism. Function Cathepsin L1 is a member of the Peptidase C1 (cathepsin) MEROPS family, which plays an important role in diverse processes including normal lysosome mediated protein turnover, antigen and proprotein processing, and apoptosis. Its substrates include collagen and elastin, as well as alpha-1 protease inhibitor, a major controlling element of neutrophil elastase activity. The encoded protein has been implicated in several pathologic processes, including myofibril necrosis in myopathies and in myocardial ischemia, and in the renal tubular response to proteinuria. This protein, which is a member of the peptidase C1 family, is a dimer composed of disulfide bond, disulfide-linked heavy and light chains, both produced from a single protein precursor. At least two transcri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathepsin W
Cathepsin W is a protein that in humans is encoded by the ''CTSW'' gene. The protein encoded by this gene, a member of the peptidase C1 family of cysteine cathepsins, is a cysteine protease cathepsin that may have a specific function in the mechanism or regulation of T-cell cytolytic activity. The encoded protein is found associated with the cell membrane inside the endoplasmic reticulum of natural killer and cytotoxic T-cells. Expression of this gene is up-regulated by interleukin-2. References Further reading * * * * * * * * * * External links * The MEROPS online database for peptidases and their inhibitorsC01.037 Proteases EC 3.4.22 Cathepsins {{gene-11-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathepsin H
Cathepsin H is a protein that in humans is encoded by the ''CTSH'' gene. The protein encoded by this gene is a cysteine cathepsin, a lysosomal cysteine protease important in the overall degradation of lysosomal proteins. It is composed of a dimer of disulfide-linked heavy and light chains, both produced from a single protein precursor. The encoded protein, which belongs to the peptidase C1 protein family, can act both as an aminopeptidase and as an endopeptidase. Increased expression of this gene has been correlated with malignant progression of prostate tumors. Two transcript variants encoding different isoforms have been found for this gene. References Further reading * * * * * * * * * * * * * * * * * * * External links * The MEROPS MEROPS is an online database for peptidases (also known as proteases, proteinases and proteolytic enzymes) and their inhibitors. The classification scheme for peptidases was published by Rawlings & Barrett in 1993, and that for protein inhibi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathepsin S
Cathepsin S is a protein that in humans is encoded by the ''CTSS'' gene. Transcript variants utilizing alternative polyadenylation signals exist for this gene. Cathepsin S is a member of the peptidase C1 family of cysteine cathepsins, a lysosomal cysteine protease that may participate in the degradation of antigenic proteins to peptides for presentation to the MHC class II. Cathepsin S can function as an elastase over a broad pH range in alveolar macrophages. Function Cathepsin S is a lysosomal enzyme that belongs to the papain-like protease of cysteine proteases. While a role in antigen presentation has long been recognized, it is now understood that cathepsin S has a role in itch and pain, or nociception. The nociceptive activity results from cathepsin S functioning as a signaling molecule via activation of protease-activated receptors 2 and 4 members of the G-protein coupled receptor family. Cathepsin S is expressed by antigen presenting cells including macrophages, B-lympho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osteoclast
An osteoclast () is a type of bone cell that breaks down bone tissue. This function is critical in the maintenance, repair, and remodeling of bones of the vertebral skeleton. The osteoclast disassembles and digests the composite of hydrated protein and mineral at a molecular level by secreting acid and a collagenase, a process known as ''bone resorption''. This process also helps regulate the level of blood calcium. Osteoclasts are found on those surfaces of bone that are undergoing resorption. On such surfaces, the osteoclasts are seen to be located in shallow depressions called ''resorption bays (Howship's lacunae)''. The resorption bays are created by the erosive action of osteoclasts on the underlying bone. The border of the lower part of an osteoclast exhibits finger-like processes due to the presence of deep infoldings of the cell membrane; this border is called ''ruffled border''. The ruffled border lies in contact with the bone surface within a resorption bay. The periph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathepsin Z
Cathepsin Z, also called cathepsin X or cathepsin P, is a protein that in humans is encoded by the ''CTSZ'' gene. It is a member of the cysteine cathepsin family of cysteine proteases, which has 11 members. As one of the 11 cathepsins, cathepsin Z contains distinctive features from others. Cathepsin Z has been reported involved in cancer malignancy and inflammation. Structure Gene The ''CTSZ'' gene is located at 20q13.32 on chromosome 20, consisting of 6 exons. At least two transcript variants of this gene have been found, but the full-length nature of only one of them has been determined. Protein Cathepsin Z is characterized by an unusual and unique 3-amino acid insertion in the highly conserved region between the glutamine of the putative oxynion hole and the active site cysteine. The pro-region of cathepsin Z shares no significant similarity with other cathepsin family sequences. It contains only 41 amino acid residues without the conserved motif of ERFNIN or GNFD found in oth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathepsin D
Cathepsin D is a protein that in humans is encoded by the ''CTSD'' gene. This gene encodes a lysosomal aspartyl protease composed of a protein dimer of disulfide-linked heavy and light chains, both produced from a single protein precursor. Cathepsin D is an aspartic endo-protease that is ubiquitously distributed in lysosomes. The main function of cathepsin D is to degrade proteins and activate precursors of bioactive proteins in pre-lysosomal compartments. This proteinase, which is a member of the peptidase A1 family, has a specificity similar to but narrower than that of pepsin A. Transcription of the ''CTSD'' gene is initiated from several sites, including one that is a start site for an estrogen-regulated transcript. Mutations in this gene are involved in the pathogenesis of several diseases, including breast cancer and possibly Alzheimer disease. Homozygous deletion of the ''CTSD'' gene leads to early lethality in the postnatal phase. Deficiency of ''CTSD'' gene has been repo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathepsin C
Cathepsin C (CTSC) also known as dipeptidyl peptidase I (DPP-I) is a lysosomal exo-cysteine protease belonging to the peptidase C1 protein family, a subgroup of the cysteine cathepsins. In humans, it is encoded by the ''CTSC'' gene. Function Cathepsin C appears to be a central coordinator for activation of many serine proteases 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathepsin F
Cathepsin F is a protein that in humans is encoded by the ''CTSF'' gene. Cysteine cathepsins are a protein family, family of cysteine proteases that represent a major component of the lysosome, lysosomal proteolytic system. In general, cathepsins contain a signal peptide, followed by a propeptide and then a catalytically active mature region. The very long (251-amino acid residues) proregion of the cathepsin F precursor contains a C-terminal domain similar to the pro-segment of cathepsin L (other), Cathepsin L-like enzymes, a 50-residue flexible linker peptide, and an N-terminal domain predicted to adopt a cystatin-like fold. The cathepsin F proregion is unique within the papain family cysteine proteases in that it contains this additional N-terminal segment predicted to share structural similarities with cysteine protease inhibitors of the cystatin superfamily. This cystatin-like domain contains some of the elements known to be important for inhibitory activity. CTSF enco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathepsin B
Cathepsin B belongs to a family of lysosomal cysteine proteases known as the cysteine cathepsins and plays an important role in intracellular proteolysis. In humans, cathepsin B is encoded by the ''CTSB'' gene. Cathepsin B is upregulated in certain cancers, in pre-malignant lesions, and in various other pathological conditions. Structure Gene The ''CTSB'' gene is located at chromosome 8p22, consisting of 13 exons. The promoter of CTSB gene contains a GC-rich region including many SP1 sites, which is similar to housekeeping genes. At least five transcript variants encoding the same protein have been found for this gene. Protein Cathepsin B is synthesized on the rough endoplasmic reticulum as a preproenzyme of 339 amino acids with a signal peptide of 17 amino acids. Procathepsin B of 43/46 kDa is then transported to the Golgi apparatus, where cathepsin B is formed. Mature cathepsin B is composed of a heavy chain of 25-26 kDa and a light chain of 5kDa, which are linked by a dime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cathepsin G
Cathepsin G is a protein that in humans is encoded by the ''CTSG'' gene. It is one of the three serine proteases of the chymotrypsin family that are stored in the azurophil granules, and also a member of the peptidase S1 protein family. Cathepsin G plays an important role in eliminating intracellular pathogens and breaking down tissues at inflammatory sites, as well as in anti-inflammatory response. Structure Gene The CTSG gene is located at chromosome 14q11.2, consisting of 5 exons. Each residue of the catalytic triad is located on a separate exon. Five polymorphisms have been identified by scanning the entire coding region. Cathepsin G is one of those homologous protease that evolved from a common ancestor by gene duplication. Protein Cathepsin G is a 255-amino-acid-residue protein including an 18-residue signal peptide, a two-residue activation peptide at the N-terminus and a carboxy terminal extension. The activity of cathepsin G depends on a catalytic triad composed of as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
