CTSD | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Aliases | CTSD , CLN10, CPSD, HEL-S-130P, cathepsin D | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 116840; MGI: 88562; HomoloGene: 55616; GeneCards: CTSD; OMA:CTSD - orthologs | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Wikidata | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Cathepsin D is a protein that in humans is encoded by the CTSD gene. [5] [6] 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. [7] The main function of cathepsin D is to degrade proteins and activate precursors of bioactive proteins in pre-lysosomal compartments. [8] 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. [6] Homozygous deletion of the CTSD gene leads to early lethality in the postnatal phase. [9] Deficiency of CTSD gene has been reported an underlying cause of neuronal ceroid lipofuscinosis (NCL). [10]
The CTSD gene is located at chromosome 11.
The catalytic sites of cathepsin D include two critical aspartic residues (amino acid 33 and 231) located on the 14 kDa and 34kDa chains. [11] The ultimate form of mature cathepsin D is composed of 337 amino acid residues, 196 amino acid residues in the heavy chain and 141 in the light chain. These two chains are linked by the hydrophobic effect. [12]
The optimum pH for cathepsin D in vitro is 4.5-5.0. [13] Cathepsin-D is an aspartic protease that depends critically on protonation of its active site Asp residue. Along with Asp-protonation, lower pH also leads to conformational switch in cathepsin-D : the N-terminal segment of the protease moves out of the active site as pH drops. [14] [15] [16] Similar to other aspartic proteases, cathepsin D accommodates up to 8 amino acid residues in the binding cleft of the active site. The main physiological functions of cathepsin D consist of metabolic degradation of intracellular proteins, activation and degradation of polypeptide hormones and growth factors, activation of enzymatic precursors, processing of enzyme activators and inhibitors, brain antigen processing and regulation of programmed cell death. [17] [18] [19] [20] Cathepsin D can also be found in the extracellular space [20] and it is one of the few cathepsins, that shows some activity at neutral pH. [21] It is able to activate the growth factors VEGF-C and VEGF-D, which might partly explain its relevance for tumor progression. [22]
The NCLs present with progressive loss of visual function and neurodevelopmental decline, seizure, myoclonic jerks and premature death. The CTSD gene is one of the identified eight genes the deficiency of which is responsible for NCLs. [10] It has been reported that a homozygous single nucleotide duplication in exon 6 could alter the reading frame and causes a premature stop codon at position 255. Over-expression of cathepsin D stimulates tumorigenicity and metastasis as well as initiation of tumor apoptosis. This protease has been regarded an independent marker of poor prognosis in breast cancer being correlated with the incidence of clinical metastasis. [23] [24] Knock-out of CTSD gene would cause intestinal necrosis and hemorrhage and increase apoptosis in thymus, indicating that cathepsin D is required in certain epithelial cells for tissue remodeling and renewal. [9] It is also reported that there might be a strong effect for CTSD genotype on Alzheimer disease risk in male. [25] Cathepsin D enzymatic activity induces hydrolytic modification of apolipoprotein B-100-containing lipoproteins, including LDL, which means it may be involved in atherosclerosis as well. [18] [26]
Serpins are a superfamily of proteins with similar structures that were first identified for their protease inhibition activity and are found in all kingdoms of life. The acronym serpin was originally coined because the first serpins to be identified act on chymotrypsin-like serine proteases. They are notable for their unusual mechanism of action, in which they irreversibly inhibit their target protease by undergoing a large conformational change to disrupt the target's active site. This contrasts with the more common competitive mechanism for protease inhibitors that bind to and block access to the protease active site.
Beta-secretase 2 is an enzyme that cleaves Glu-Val-Asn-Leu!Asp-Ala-Glu-Phe in the Swedish variant of Alzheimer's amyloid precursor protein. BACE2 is a close homolog of BACE1.
Cathepsins are proteases 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.
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 K, abbreviated CTSK, is an enzyme that in humans is encoded by the CTSK gene.
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.
Aspartic proteases are a catalytic type of protease enzymes that use an activated water molecule bound to one or more aspartate residues for catalysis of their peptide substrates. In general, they have two highly conserved aspartates in the active site and are optimally active at acidic pH. Nearly all known aspartyl proteases are inhibited by pepstatin.
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.
Proteinase-activated receptor 1 (PAR1) also known as protease-activated receptor 1, coagulation factor II receptor and thrombin receptor is a protein that in humans is encoded by the F2R gene. PAR1 is a G protein-coupled receptor and one of four protease-activated receptors involved in the regulation of thrombotic response. Highly expressed in platelets and endothelial cells, PAR1 plays a key role in mediating the interplay between coagulation and inflammation, which is important in the pathogenesis of inflammatory and fibrotic lung diseases. It is also involved both in disruption and maintenance of endothelial barrier integrity, through interaction with either thrombin or activated protein C, respectively.
Cathepsin L1 is a protein that in humans is encoded by the CTSL1 gene. The protein is a cysteine cathepsin, a lysosomal cysteine protease that plays a major role in intracellular protein catabolism.
Antileukoproteinase, also known as secretory leukocyte protease inhibitor (SLPI), is an enzyme that in humans is encoded by the SLPI gene. SLPI is a highly cationic single-chain protein with eight intramolecular disulfide bonds. It is found in large quantities in bronchial, cervical, and nasal mucosa, saliva, and seminal fluids. SLPI inhibits human leukocyte elastase, human cathepsin G, human trypsin, neutrophil elastase, and mast cell chymase. X-ray crystallography has shown that SLPI has two homologous domains of 53 and 54 amino acids, one of which exhibits anti-protease activity. The other domain is not known to have any function.
Cystatin-A is a protein that in humans is encoded by the CSTA gene.
Lysosomal-associated membrane protein 1 (LAMP-1) also known as lysosome-associated membrane glycoprotein 1 and CD107a, is a protein that in humans is encoded by the LAMP1 gene. The human LAMP1 gene is located on the long arm (q) of chromosome 13 at region 3, band 4 (13q34).
Cathepsin E is an enzyme that in humans is encoded by the CTSE gene. The enzyme is also known as slow-moving proteinase, erythrocyte membrane aspartic proteinase, SMP, EMAP, non-pepsin proteinase, cathepsin D-like acid proteinase, cathepsin E-like acid proteinase, cathepsin D-type proteinase) is an enzyme.
Cathepsin H is a protein that in humans is encoded by the CTSH gene.
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.
Legumain is a protein that in humans is encoded by the LGMN gene.
Cathepsin L2 is a protein encoded in humans by the CTSV gene.
Cathepsin F is a protein that in humans is encoded by the CTSF gene.
Papain-like proteases are a large protein family of cysteine protease enzymes that share structural and 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.