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0  structures 86  species 0  interactions 91  sequences 1  architecture

Family: Peptidase_U9 (PF03420)

Summary: Prohead core protein protease

Pfam includes annotations and additional family information from a range of different sources. These sources can be accessed via the tabs below.

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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.

Prohead core protein protease Provide feedback

No Pfam abstract.

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR005082

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 peptidases families associated with clan U- have an unknown catalytic mechanism as the protein fold of the active site domain and the active site residues have not been reported.

This group of peptidases belongs to MEROPS peptidase family U9 (phage prohead processing peptidase family, clan U-), which play a role in the head assembly of Bacteriophage T4.

The pathway of bacteriophage T4 head assembly begins with the formation of a prohead bound to the bacterial cell membrane which is later converted to the mature, DNA-containing head. During maturation, all but one of the prohead proteins are proteolytically processed by a phage-coded protease which is formed by autocatalytic cleavage of the product of gene 21 (gp21). Protease gp21 has been tentatively located in the centre of the prohead core [PUBMED:3552886].

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_SH (CL0201), which has the following description:

This clan includes the serine peptidase assemblin from herpes virus as well as other viral peptidase families predicted to be related [1].

The clan contains the following 4 members:

Peptidase_S21 Peptidase_U35 Peptidase_U35_2 Peptidase_U9

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
(2)
Full
(91)
Representative proteomes NCBI
(81)
Meta
(1485)
RP15
(3)
RP35
(5)
RP55
(6)
RP75
(6)
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PP/heatmap 1 View  View  View  View  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
(2)
Full
(91)
Representative proteomes NCBI
(81)
Meta
(1485)
RP15
(3)
RP35
(5)
RP55
(6)
RP75
(6)
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
(2)
Full
(91)
Representative proteomes NCBI
(81)
Meta
(1485)
RP15
(3)
RP35
(5)
RP55
(6)
RP75
(6)
Raw Stockholm Download   Download   Download   Download   Download   Download   Download   Download  
Gzipped Download   Download   Download   Download   Download   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.

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: Bateman A
Number in seed: 2
Number in full: 91
Average length of the domain: 196.80 aa
Average identity of full alignment: 38 %
Average coverage of the sequence by the domain: 87.65 %

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 22.0 22.0
Trusted cut-off 22.1 39.2
Noise cut-off 20.0 21.9
Model length: 213
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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