Summary: Putative binding domain
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This is the Wikipedia entry entitled "Caspase". More...
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Caspase Edit Wikipedia article
Structure of interleukin-1 beta-converting enzyme.
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.
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[update], twelve caspases have been identified in humans. 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, are not currently classified as initiator or effector in MeSH, because they are inflammatory enzymes that, in concert with CASP1, are involved in T-cell maturation.
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:
- granzyme B (released by cytotoxic T lymphocytes and NK cells), which is known to activate caspase-3 and -7
- death receptors (like Fas, TRAIL receptors and TNF receptor), which can activate caspase-8 and -10
- the apoptosome (regulated by cytochrome c and the Bcl-2 family), which activates caspase-9.
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.
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. 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. 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.
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.
- The Proteolysis Map
- Programmed cell death
- 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.
- 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.
- HUGO Gene Nomenclature Committee
- 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]
- NIH Medical Subject Headings
- 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.
- . 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.
- 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.
- 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.
- 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.
- Eukaryotic Linear Motif resource motif class CLV_C14_Caspase3-7
- Apoptosis Video Demonstrates a model of a caspase cascade as it occurs in vivo.
- The Mechanisms of Apoptosis Kimball's Biology Pages. Simple explanation of the mechanisms of apoptosis triggered by internal signals (bcl-2), along the caspase-9, caspase-3 and caspase-7 pathway; and by external signals (FAS and TNF), along the caspase 8 pathway. Accessed 25 March 2007.
- Apoptosis & Caspase 7, PMAP-animation
- Caspases at the US National Library of Medicine Medical Subject Headings (MeSH)
- Tumors Beware (from Beaker Blog)
This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.
Putative binding domain Provide feedback
This short domain is often found nested inside other longer domains. The function is not known, but the domain carries a highly conserved GVQW motif. The members are rich in proline and cysteine. This may be a binding domain.
External database links
This tab holds annotation information from the InterPro database.
No InterPro data for this Pfam family.
Below is a listing of the unique domain organisations or architectures in which this domain is found. More...
The graphic that is shown by default represents the longest sequence with a given architecture. Each row contains the following information:
- the number of sequences which exhibit this architecture
a textual description of the architecture, e.g. Gla, EGF x 2, Trypsin.
This example describes an architecture with one
Gladomain, followed by two consecutive
EGFdomains, and finally a single
- a link to the page in the Pfam site showing information about the sequence that the graphic describes
- the UniProt description of the protein sequence
- the number of residues in the sequence
- the Pfam graphic itself.
Note that you can see the family page for a particular domain by clicking on the graphic. You can also choose to see all sequences which have a given architecture by clicking on the Show link in each row.
Finally, because some families can be found in a very large number of architectures, we load only the first fifty architectures by default. If you want to see more architectures, click the button at the bottom of the page to load the next set.
Loading domain graphics...
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 .
The clan contains the following 9 members:CHAT GVQW Peptidase_C11 Peptidase_C13 Peptidase_C14 Peptidase_C25 Peptidase_C50 Peptidase_C80 Raptor_N
We store a range of different sequence alignments for families. As well as the seed alignment from which the family is built, we provide the full alignment, generated by searching the sequence database using the family HMM. We also generate alignments using four representative proteomes (RP) sets, the NCBI sequence database, and our metagenomics sequence database. More...
There are various ways to view or download the sequence alignments that we store. We provide several sequence viewers and a plain-text Stockholm-format file for download.
We make a range of alignments for each Pfam-A family:
- the curated alignment from which the HMM for the family is built
- the alignment generated by searching the sequence database using the HMM
- Representative Proteomes (RPs) at 15%, 35%, 55% and 75% co-membership thresholds
- alignment generated by searching the NCBI sequence database using the family HMM
- alignment generated by searching the metagenomics sequence database using the family HMM
You can see the alignments as HTML or in three different sequence viewers:
- a Java applet developed at the University of Dundee. You will need Java installed before running jalview
- an HTML page showing the whole alignment.Please note: full Pfam alignments can be very large. These HTML views are extremely large and often cause problems for browsers. Please use either jalview or the Pfam viewer if you have trouble viewing the HTML version
- an HTML-based representation of the alignment, coloured according to the posterior-probability (PP) values from the HMM. As for the standard HTML view, heatmap alignments can also be very large and slow to render.
- Pfam viewer
- an HTML-based viewer that uses DAS to retrieve alignment fragments on request
You can download (or view in your browser) a text representation of a Pfam alignment in various formats:
You can also change the order in which sequences are listed in the alignment, change how insertions are represented, alter the characters that are used to represent gaps in sequences and, finally, choose whether to download the alignment or to view it in your browser directly.
You may find that large alignments cause problems for the viewers and the reformatting tool, so we also provide all alignments in Stockholm format. You can download either the plain text alignment, or a gzipped version of it.
We make a range of alignments for each Pfam-A family. You can see a description of each above. You can view these alignments in various ways but please note that some types of alignment are never generated while others may not be available for all families, most commonly because the alignments are too large to handle.
1Cannot generate PP/Heatmap alignments for seeds; no PP data available
Key: available, not generated, — not available.
Format an alignment
We make all of our alignments available in Stockholm format. You can download them here as raw, plain text files or as gzip-compressed files.
You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.
MyHits provides a collection of tools to handle multiple sequence alignments. For example, one can refine a seed alignment (sequence addition or removal, re-alignment or manual edition) and then search databases for remote homologs using HMMER3.
HMM logos is one way of visualising profile HMMs. Logos provide a quick overview of the properties of an HMM in a graphical form. You can see a more detailed description of HMM logos and find out how you can interpret them here. More...
If you find these logos useful in your own work, please consider citing the following article:
This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.
Note: You can also download the data file for the tree.
Curation and family details
This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.
|Number in seed:||35|
|Number in full:||1257|
|Average length of the domain:||41.40 aa|
|Average identity of full alignment:||60 %|
|Average coverage of the sequence by the domain:||18.50 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||1|
|Download:||download the raw HMM for this family|
Weight segments by...
Change the size of the sunburst
selected sequences to HMM
a FASTA-format file
- 0 sequences
- 0 species
This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the More....
This chart is a modified "sunburst" visualisation of the species tree for this family. It shows each node in the tree as a separate arc, arranged radially with the superkingdoms at the centre and the species arrayed around the outermost ring.
How the sunburst is generated
The tree is built by considering the taxonomic lineage of each sequence that has a match to this family. For each node in the resulting tree, we draw an arc in the sunburst. The radius of the arc, its distance from the root node at the centre of the sunburst, shows the taxonomic level ("superkingdom", "kingdom", etc). The length of the arc represents either the number of sequences represented at a given level, or the number of species that are found beneath the node in the tree. The weighting scheme can be changed using the sunburst controls.
In order to reduce the complexity of the representation, we reduce the number of taxonomic levels that we show. We consider only the following eight major taxonomic levels:
Colouring and labels
Segments of the tree are coloured approximately according to their superkingdom. For example, archeal branches are coloured with shades of orange, eukaryotes in shades of purple, etc. The colour assignments are shown under the sunburst controls. Where space allows, the name of the taxonomic level will be written on the arc itself.
As you move your mouse across the sunburst, the current node will be highlighted. In the top section of the controls panel we show a summary of the lineage of the currently highlighed node. If you pause over an arc, a tooltip will be shown, giving the name of the taxonomic level in the title and a summary of the number of sequences and species below that node in the tree.
Anomalies in the taxonomy tree
There are some situations that the sunburst tree cannot easily handle and for which we have work-arounds in place.
Missing taxonomic levels
Some species in the taxonomic tree may not have one or more of the main eight levels that we display. For example, Bos taurus is not assigned an order in the NCBI taxonomic tree. In such cases we mark the omitted level with, for example, "No order", in both the tooltip and the lineage summary.
Unmapped species names
The tree is built by looking at each sequence in the full alignment for the family. We take the name of the species given by UniProt and try to map that to the full taxonomic tree from NCBI. In some cases, the name chosen by UniProt does not map to any node in the NCBI tree, perhaps because the chosen name is listed as a synonym or a misspelling in the NCBI taxonomy.
So that these nodes are not simply omitted from the sunburst tree, we group them together in a separate branch (or segment of the sunburst tree). Since we cannot determine the lineage for these unmapped species, we show all levels between the superkingdom and the species as "uncategorised".
Since we reduce the species tree to only the eight main taxonomic levels, sequences that are mapped to the sub-species level in the tree would not normally be shown. Rather than leave out these species, we map them instead to their parent species. So, for example, for sequences belonging to one of the Vibrio cholerae sub-species in the NCBI taxonomy, we show them instead as belonging to the species Vibrio cholerae.
Too many species/sequences
For large species trees, you may see blank regions in the outer layers of the sunburst. These occur when there are large numbers of arcs to be drawn in a small space. If an arc is less than approximately one pixel wide, it will not be drawn and the space will be left blank. You may still be able to get some information about the species in that region by moving your mouse across the area, but since each arc will be very small, it will be difficult to accurately locate a particular species.
The tree shows the occurrence of this domain across different species. More...
We show the species tree in one of two ways. For smaller trees we try to show an interactive representation, which allows you to select specific nodes in the tree and view them as an alignment or as a set of Pfam domain graphics.
Unfortunately we have found that there are problems viewing the interactive tree when the it becomes larger than a certain limit. Furthermore, we have found that Internet Explorer can become unresponsive when viewing some trees, regardless of their size. We therefore show a text representation of the species tree when the size is above a certain limit or if you are using Internet Explorer to view the site.
If you are using IE you can still load the interactive tree by clicking the "Generate interactive tree" button, but please be aware of the potential problems that the interactive species tree can cause.
For all of the domain matches in a full alignment, we count the number that are found on all sequences in the alignment. This total is shown in the purple box.
We also count the number of unique sequences on which each domain is found, which is shown in green. Note that a domain may appear multiple times on the same sequence, leading to the difference between these two numbers.
Finally, we group sequences from the same organism according to the NCBI code that is assigned by UniProt, allowing us to count the number of distinct sequences on which the domain is found. This value is shown in the pink boxes.
We use the NCBI species tree to group organisms according to their taxonomy and this forms the structure of the displayed tree. Note that in some cases the trees are too large (have too many nodes) to allow us to build an interactive tree, but in most cases you can still view the tree in a plain text, non-interactive representation. Those species which are represented in the seed alignment for this domain are highlighted.
You can use the tree controls to manipulate how the interactive tree is displayed:
- show/hide the summary boxes
- highlight species that are represented in the seed alignment
- expand/collapse the tree or expand it to a given depth
- select a sub-tree or a set of species within the tree and view them graphically or as an alignment
- save a plain text representation of the tree
Please note: for large trees this can take some time. While the tree is loading, you can safely switch away from this tab but if you browse away from the family page entirely, the tree will not be loaded.