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20  structures 9  species 1  interaction 29  sequences 1  architecture

Family: Peptidase_A21 (PF03566)

Summary: Peptidase family A21

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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.

Peptidase family A21 Provide feedback

No Pfam abstract.

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR005313

In the MEROPS database peptidases and peptidase homologues are grouped into clans and families. Clans are groups of families for which there is evidence of common ancestry based on a common structural fold:

  • Each clan is identified with two letters, the first representing the catalytic type of the families included in the clan (with the letter 'P' being used for a clan containing families of more than one of the catalytic types serine, threonine and cysteine). Some families cannot yet be assigned to clans, and when a formal assignment is required, such a family is described as belonging to clan A-, C-, M-, N-, S-, T- or U-, according to the catalytic type. Some clans are divided into subclans because there is evidence of a very ancient divergence within the clan, for example MA(E), the gluzincins, and MA(M), the metzincins.
  • Peptidase families are grouped by their catalytic type, the first character representing the catalytic type: A, aspartic; C, cysteine; G, glutamic acid; M, metallo; N, asparagine; S, serine; T, threonine; and U, unknown. The serine, threonine and cysteine peptidases utilise the amino acid as a nucleophile and form an acyl intermediate - these peptidases can also readily act as transferases. In the case of aspartic, glutamic and metallopeptidases, the nucleophile is an activated water molecule. In the case of the asparagine endopeptidases, the nucleophile is asparagine and all are self-processing endopeptidases.

In many instances the structural protein fold that characterises the clan or family may have lost its catalytic activity, yet retain its function in protein recognition and binding.

The asparagine endopeptidases are all autocatalytic endopeptidases utilizing Asn at position P1. Cleavage occurs as a consequence of cyclization of the Asn residue [PUBMED:16246842].

This group of peptidases belongs to the MEROPS family N2 (clan NA). In the Nudaurelia capensis omega virus capsid protein the residues that form the catalytic dyad in the active site are Glu103 and Asn570. The cleavage mediated by the enzyme is an autolytic one, and the catalytic Asn is also the P1 residue in the cleavage site, Asn570-|-Phe571 releasing a 74-residue fragment from the C terminus of the coat protein. This cleavage occurs during the late stages of virion assembly. Heterologous expression of the coat protein gene of tetravirus in a baculovirus system results in the spontaneous assembly of virus-like particles (VLPs) that remain uncleaved when purified at neutral pH [PUBMED:15659373].

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 Viral_ssRNA_CP (CL0055), which has the following description:

The clan contains a set of viral coat protein families and peptidase A6. The only known peptidase activity is an autolytic cleavage releasing a 44-residue C-terminal fragment. The reaction is very slow and only occurs within the assembled virion. There is debate whether this is actually a true peptidase. The virion with these coat or capsid proteins are icosahedral viruses containing sixty triangular coat protein units, each unit consisting of three proteins. The coat protein consists of two subdomains, an eight-stranded beta-barrel on the surface and a three-helix bundle on the inner face.

The clan contains the following 17 members:

Birna_VP2 Bromo_coat Calici_coat Capsid-VNN Circo_capsid Como_LCP CRPV_capsid Cucumo_coat Luteo_coat Nepo_coat Peptidase_A21 Peptidase_A6 Rhv SP2 TT_ORF1 Tymo_coat Viral_coat

Alignments

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...

View options

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.

  Seed
(5)
Full
(29)
Representative proteomes NCBI
(36)
Meta
(0)
RP15
(0)
RP35
(0)
RP55
(0)
RP75
(0)
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PP/heatmap 1 View             
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1Cannot generate PP/Heatmap alignments for seeds; no PP data available

Key: ✓ available, x not generated, not available.

Format an alignment

  Seed
(5)
Full
(29)
Representative proteomes NCBI
(36)
Meta
(0)
RP15
(0)
RP35
(0)
RP55
(0)
RP75
(0)
Alignment:
Format:
Order:
Sequence:
Gaps:
Download/view:

Download options

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.

  Seed
(5)
Full
(29)
Representative proteomes NCBI
(36)
Meta
(0)
RP15
(0)
RP35
(0)
RP55
(0)
RP75
(0)
Raw Stockholm Download   Download           Download    
Gzipped Download   Download           Download    

You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

External links

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.

Pfam alignments:

HMM logo

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...

Trees

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.

Curation View help on the curation process

Seed source: MEROPS
Previous IDs: none
Type: Family
Author: Griffiths-Jones SR
Number in seed: 5
Number in full: 29
Average length of the domain: 607.00 aa
Average identity of full alignment: 68 %
Average coverage of the sequence by the domain: 93.74 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 25.0 25.0
Trusted cut-off 46.0 25.0
Noise cut-off 19.0 18.6
Model length: 648
Family (HMM) version: 8
Download: download the raw HMM for this family

Species distribution

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This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the adjacent tab. More...

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Interactions

There is 1 interaction for this family. More...

Peptidase_A21

Structures

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_A21 domain has been found. There are 20 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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