Summary: Prohead core protein protease
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].
- 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
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This clan includes the serine peptidase assemblin from herpes virus as well as other viral peptidase families predicted to be related .
The clan contains the following 4 members:Peptidase_S21 Peptidase_U35 Peptidase_U35_2 Peptidase_U9
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:
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Curation and family details
|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 build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||8|
|Download:||download the raw HMM for this family|
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