Caspase 2 also known as CASP2 is an enzyme that, in humans, is encoded by the CASP2 gene. [5] CASP2 orthologs [6] have been identified in nearly all mammals for which complete genome data are available. Unique orthologs are also present in birds, lizards, lissamphibians, and teleosts.
Sequential activation of caspases plays a central role in the execution-phase of cell apoptosis. Caspases exist as inactive proenzymes that undergo proteolytic processing at conserved aspartic residues to produce two subunits, large and small, that dimerize to form the active enzyme. The proteolytic cleavage of this protein is induced by a variety of apoptotic stimuli. [7]
Caspase 2 proteolytically cleaves other proteins. It belongs to a family of cysteine proteases called caspases that cleave proteins only at an amino acid following an aspartic acid residue. Within this family, caspase 2 is part of the Ich-1 subfamily. It is one of the most conserved caspases in different species of animal. Caspase 2 has a similar amino acid sequence to initiator caspases, including caspase 1, caspase 4, caspase 5, and caspase 9. It is produced as a zymogen, which contains a long pro-domain that is similar to that of caspase 9 and contains a protein interaction domain known as a CARD domain. Pro-caspase-2 contains two subunits, p19 and p12.
It has been shown to associate with several proteins involved in apoptosis using its CARD domain, including RIP-associated Ich-1/Ced-3-homologue protein with a death domain (RAIDD), apoptosis repressor with caspase recruitment domain (ARC), and death effector filament-forming Ced-4-like apoptosis protein (DEFCAP). [8] Together with RAIDD and p53-induced protein with a death domain ([PIDD])(LRDD), caspase 2 has been shown to form the so-called PIDDosome, [9] which may serve as an activation platform for the protease, although it may also be activated in the absence of PIDD. [10] Overall, caspase 2 appears to be a very versatile caspase with multiple functions beyond cell death induction. [11] [12]
Caspase 2 has been shown to interact with:
Caspases are a family of protease enzymes playing essential roles in programmed cell death. They are named caspases due to their specific cysteine protease activity – a cysteine in its active site nucleophilically attacks and cleaves a target protein only after an aspartic acid residue. As of 2009, there are 12 confirmed caspases in humans and 10 in mice, carrying out a variety of cellular functions.
Caspase recruitment domains, or caspase activation and recruitment domains (CARDs), are interaction motifs found in a wide array of proteins, typically those involved in processes relating to inflammation and apoptosis. These domains mediate the formation of larger protein complexes via direct interactions between individual CARDs. CARDs are found on a strikingly wide range of proteins, including helicases, kinases, mitochondrial proteins, caspases, and other cytoplasmic factors.
The BH3 interacting-domain death agonist, or BID, gene is a pro-apoptotic member of the Bcl-2 protein family. Bcl-2 family members share one or more of the four characteristic domains of homology entitled the Bcl-2 homology (BH) domains, and can form hetero- or homodimers. Bcl-2 proteins act as anti- or pro-apoptotic regulators that are involved in a wide variety of cellular activities.
Caspase-9 is an enzyme that in humans is encoded by the CASP9 gene. It is an initiator caspase, critical to the apoptotic pathway found in many tissues. Caspase-9 homologs have been identified in all mammals for which they are known to exist, such as Mus musculus and Pan troglodytes.
Caspase-8 is a caspase protein, encoded by the CASP8 gene. It most likely acts upon caspase-3. CASP8 orthologs have been identified in numerous mammals for which complete genome data are available. These unique orthologs are also present in birds.
Caspase-3 is a caspase protein that interacts with caspase-8 and caspase-9. It is encoded by the CASP3 gene. CASP3 orthologs have been identified in numerous mammals for which complete genome data are available. Unique orthologs are also present in birds, lizards, lissamphibians, and teleosts.
Caspase-7, apoptosis-related cysteine peptidase, also known as CASP7, is a human protein encoded by the CASP7 gene. CASP7 orthologs have been identified in nearly all mammals for which complete genome data are available. Unique orthologs are also present in birds, lizards, lissamphibians, and teleosts.
Caspase-6 is an enzyme that in humans is encoded by the CASP6 gene. CASP6 orthologs have been identified in numerous mammals for which complete genome data are available. Unique orthologs are also present in birds, lizards, lissamphibians, and teleosts. Caspase-6 has known functions in apoptosis, early immune response and neurodegeneration in Huntington's and Alzheimer's disease.
Baculoviral IAP repeat-containing protein3 is a protein that in humans is encoded by the BIRC3 gene.
Baculoviral IAP repeat-containing protein 2 is a protein that in humans is encoded by the BIRC2 gene.
Caspase-10 is an enzyme that, in humans, is encoded by the CASP10 gene.
Death receptor 5 (DR5), also known as TRAIL receptor 2 (TRAILR2) and tumor necrosis factor receptor superfamily member 10B (TNFRSF10B), is a cell surface receptor of the TNF-receptor superfamily that binds TRAIL and mediates apoptosis.
Apoptotic protease activating factor 1, also known as APAF1, is a human homolog of C. elegans CED-4 gene.
B-cell lymphoma/leukemia 10 is a protein that in humans is encoded by the BCL10 gene. Like BCL2, BCL3, BCL5, BCL6, BCL7A, and BCL9, it has clinical significance in lymphoma.
PYCARD, often referred to as ASC, is a protein that in humans is encoded by the PYCARD gene. It is localized mainly in the nucleus of monocytes and macrophages. In case of pathogen infection, however, it relocalizes rapidly to the cytoplasm, perinuclear space, endoplasmic reticulum and mitochondria and it is a key adaptor protein in activation of the inflammasome.
Serine protease HTRA2, mitochondrial is an enzyme that in humans is encoded by the HTRA2 gene. This protein is involved in caspase-dependent apoptosis and in Parkinson's disease.
NLRP1 encodes NACHT, LRR, FIIND, CARD domain and PYD domains-containing protein 1 in humans. NLRP1 was the first protein shown to form an inflammasome. NLRP1 is expressed by a variety of cell types, which are predominantly epithelial or hematopoietic. The expression is also seen within glandular epithelial structures including the lining of the small intestine, stomach, airway epithelia and in hairless or glabrous skin. NLRP1 polymorphisms are associated with skin extra-intestinal manifestations in CD. Its highest expression was detected in human skin, in psoriasis and in vitiligo. Polymorphisms of NLRP1 were found in lupus erythematosus and diabetes type 1. Variants of mouse NLRP1 were found to be activated upon N-terminal cleavage by the protease in anthrax lethal factor.
Death domain-containing protein CRADD is a protein that in humans is encoded by the CRADD gene.
Leucine-rich repeats and death domain containing, also known as LRDD or p53-induced protein with a death domain (PIDD), is a protein which in humans is encoded by the LRDD gene.
Death effector domain containing protein is a protein that in humans is encoded by the DEDD gene.
This article incorporates text from the United States National Library of Medicine, which is in the public domain.
