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565  structures 726  species 4  interactions 3842  sequences 299  architectures

Family: Peptidase_C14 (PF00656)

Summary: Caspase domain

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Caspase Edit Wikipedia article

Caspase domain
PDB 1ice EBI.jpg
Structure of interleukin-1 beta-converting enzyme.[1]
Symbol Peptidase_C14
Pfam PF00656
Pfam clan CL0093
InterPro IPR002398
SCOP 1ice

Caspases, or cysteine-aspartic proteases or cysteine-dependent aspartate-directed proteases are a family of cysteine proteases that play essential roles in apoptosis (programmed cell death), necrosis, and inflammation.[2]

Caspases are essential in cells for apoptosis, or programmed cell death, in development and most other stages of adult life, and have been termed "executioner" proteins for their roles in the cell. Some caspases are also required in the immune system for the maturation of lymphocytes. Failure of apoptosis is one of the main contributions to tumour development and autoimmune diseases; this, coupled with the unwanted apoptosis that occurs with ischemia or Alzheimer's disease, has stimulated interest in caspases as potential therapeutic targets since they were discovered in the mid-1990s.

Types of caspase proteins

As of November 2009, twelve caspases have been identified in humans.[3] There are two types of apoptotic caspases: initiator (apical) caspases and effector (executioner) caspases. Initiator caspases (e.g., CASP2, CASP8, CASP9, and CASP10) cleave inactive pro-forms of effector caspases, thereby activating them. Effector caspases (e.g., CASP3, CASP6, CASP7) in turn cleave other protein substrates within the cell, to trigger the apoptotic process. The initiation of this cascade reaction is regulated by caspase inhibitors.

CASP4 and CASP5, which are overexpressed in some cases of vitiligo and associated autoimmune diseases caused by NALP1 variants,[4] are not currently classified as initiator or effector in MeSH,[5] because they are inflammatory enzymes that, in concert with CASP1, are involved in T-cell maturation.

Caspase cascade

Caspases are regulated at a post-translational level, ensuring that they can be rapidly activated. They are first synthesized as inactive pro-caspases, that consist of a prodomain, a small subunit and a large subunit. Initiator caspases possess a longer prodomain than the effector caspases, whose prodomain is very small. The prodomain of the initiator caspases contain domains such as a CARD domain (e.g., caspases-2 and caspase-9) or a death effector domain (DED) (caspases-8 and caspase-10) that enables the caspases to interact with other molecules that regulate their activation. These molecules respond to stimuli that cause the clustering of the initiator caspases. Such clustering allows them to activate automatically, so that they can proceed to activate the effector caspases.

The caspase cascade can be activated by:

Overview of signal transduction pathways involved in apoptosis.

Some of the final targets of caspases include:

  • nuclear lamins
  • ICAD/DFF45 (inhibitor of caspase activated DNase or DNA fragmentation factor 45)
  • PARP (poly-ADP ribose polymerase)
  • PAK2 (P 21-activated kinase 2).

The role of caspase substrate cleavage in the morphology of apoptosis is not clear. However, ICAD/DFF45 acts to restrain CAD (caspase-activated DNase). The cleavage and inactivation of ICAD/DFF45 by a caspase allows CAD to enter the nucleus and fragment the DNA, causing the characteristic 'DNA ladder' in apoptotic cells.

In 2009, Queensland researchers announced caspase 1 and 3 in macrophages are regulated by p202 (a double-stranded DNA binding protein) reducing caspase response, and AIM2 (another double-stranded DNA binding protein) increasing caspase activation.[1]

Discovery of caspases, functions

H. Robert Horvitz initially established the importance of caspases in apoptosis and found that the ced-3 gene is required for the cell death that took place during the development of the nematode C. elegans. Horvitz and his colleague Junying Yuan found in 1993 that the protein encoded by the ced-3 gene is cysteine protease with similar properties to the mammalian interleukin-1-beta converting enzyme (ICE) (now known as caspase 1), which at the time was the only known caspase.[6] Other mammalian caspases were subsequently identified, in addition to caspases in organisms such as fruit fly Drosophila melanogaster.

Researchers decided upon the nomenclature of the caspase in 1996. In many instances, a particular caspase had been identified simultaneously by more than one laboratory, who would each give the protein a different name. For example, caspase 3 was variously known as CPP32, apopain and Yama. Caspases, therefore, were numbered in the order in which they were identified.[2] ICE was, therefore, renamed as caspase 1. ICE was the first mammalian caspase to be characterised because of its similarity to the nematode death gene ced-3, but it appears that the principal role of this enzyme is to mediate inflammation rather than cell death.

For the discovery of caspases and other aspects of apoptosis, see articles by Danial and Korsmeyer,[7] Yuan and Horvitz,[8] and by Li et al.[9] in the January 23, 2004 edition of the journal Cell.

Recent studies have demonstrated that caspase proteases are also regulators of non-death functions, the most notable ones being those involving the maturation of a wide variety of cells such as red blood cells and skeletal muscle myoblasts.[10]

See also


  1. ^ Wilson KP, Black JA, Thomson JA; et al. (July 1994). "Structure and mechanism of interleukin-1 beta converting enzyme". Nature 370 (6487): 270–5. doi:10.1038/370270a0. PMID 8035875. 
  2. ^ a b Alnemri ES, Emad S; et al. (1996). "Human ICE/CED-3 Protease Nomenclature". Cell 87 (2): 171. doi:10.1016/S0092-8674(00)81334-3. PMID 8861900. Retrieved 6 March 2011. 
  3. ^ HUGO Gene Nomenclature Committee
  4. ^ Gregersen, P.K. (22 March 2007). "Modern genetics, ancient defenses, and potential therapies". N Engl J Med. 356 (12): 1263–6. doi:10.1056/NEJMe078017. PMID 17377166. [PMID 17377166]
  5. ^ NIH Medical Subject Headings
  6. ^ Yuan, J; et al. (1993). "The C. elegans cell death gene ced-3 encodes a protein similar to mammalian interleukin-1 beta-converting enzyme". Cell 75 (4): 641–652. doi:10.1016/0092-8674(93)90485-9. PMID 8242740. 
  7. ^ . Danial, N. N.; Korsmeyer, S. J. (January 2004). "Cell Death: Critical Control Points". Cell 116 (2): 205–219. doi:10.1016/S0092-8674(04)00046-7. PMID 14744432. Retrieved 2006-11-06. 
  8. ^ Yuan, J.; Horvitz, H. R. (January 2004). "A First Insight into the Molecular Mechanisms of Apoptosis". Cell 116 (2 Suppl): 53–56. doi:10.1016/S0092-8674(04)00028-5. PMID 15055582. Retrieved 2006-11-06. 
  9. ^ Li, P.; et al. (January 2004). "Mitochondrial Activation of Apoptosis". Cell 116 (2 Suppl): 57–59. doi:10.1016/S0092-8674(04)00031-5. PMID 15055583. Retrieved 2006-11-06. 
  10. ^ Lamkanfi, M.; et al. (January 2007). "Caspases in cell survival, proliferation and differentiation". Cell Death and Differentiation 14 (1): 44–55. doi:10.1038/sj.cdd.4402047. PMID 17053807. Retrieved 2011-02-28. 

External links

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Literature references

  1. Wilson KP, Black JA, Thomson JA, Kim EE, Griffith JP, Navia MA, Murcko MA, Chambers SP, Aldape RA, Raybuck SA, et al , Nature 1994;370:270-275.: Structure and mechanism of interleukin-1 beta converting enzyme. PUBMED:8035875 EPMC:8035875

Internal database links

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR011600

This domain can be found in caspases (MEROPS family C12A) and metacaspases (MEROPS family C14B). Metacaspases adopt a caspase fold, with active site loops arranged similarly as other caspases [PUBMED:22761449].

Caspases (Cysteine-dependent ASPartyl-specific proteASE) are cysteine peptidases [PUBMED:11517925]. They are tightly regulated proteins that require zymogen activation to become active, and once active can be regulated by caspase inhibitors. Caspases are mainly involved in mediating cell death (apoptosis) [PUBMED:10578171, PUBMED:10872455, PUBMED:15077141]. They have two main roles within the apoptosis cascade: as initiators that trigger the cell death process, and as effectors of the process itself. Caspases can have roles other than in apoptosis, such as caspase-1 (interleukin-1 beta convertase) (EC), which is involved in the inflammatory process. The activation of apoptosis can sometimes lead to caspase-1 activation, providing a link between apoptosis and inflammation, such as during the targeting of infected cells. Caspases may also be involved in cell differentiation [PUBMED:15066636].

Metacaspases are arginine/lysine-specific, in contrast to caspases, which are aspartate-specific. They are found only in plants [PUBMED:17998208, PUBMED:23522353], fungi [PUBMED:18355456] and lower eukaryotes, including the protozoa [PUBMED:23506317]. While plant metacaspases have been shown to be involved in cell death pathways, in other organisms they have evolved alternative functions [PUBMED:21949125].

Gene Ontology

The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.

Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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Pfam Clan

This family is a member of clan Peptidase_CD (CL0093), which has the following description:

The members of this clan are all endopeptidase that have the catalytic dyad histidine followed by cysteine. The catalytic histidine is preceded by a block of hydrophobic residues and a glycine, where as the cysteine is preceded by a block of hydrophobic residues and a glutamine and an alanine. The members with a know structure adopt an alpha/beta fold [1].

The clan contains the following 8 members:

CHAT Peptidase_C11 Peptidase_C13 Peptidase_C14 Peptidase_C25 Peptidase_C50 Peptidase_C80 Raptor_N


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Curation and family details

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Curation View help on the curation process

Seed source: Bateman A & Pfam-B_2524 (Release 8.0)
Previous IDs: ICE_p20;
Type: Domain
Author: Bateman A
Number in seed: 115
Number in full: 3842
Average length of the domain: 237.50 aa
Average identity of full alignment: 16 %
Average coverage of the sequence by the domain: 49.18 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 11927849 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 21.4 21.4
Trusted cut-off 21.4 21.4
Noise cut-off 21.3 21.3
Model length: 248
Family (HMM) version: 19
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Species distribution

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Archea Archea Eukaryota Eukaryota
Bacteria Bacteria Other sequences Other sequences
Viruses Viruses Unclassified Unclassified
Viroids Viroids Unclassified sequence Unclassified sequence


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There are 4 interactions for this family. More...

BIR Peptidase_C14 BIR P35


For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Peptidase_C14 domain has been found. There are 565 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.

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