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55  structures 646  species 3  interactions 1638  sequences 94  architectures

Family: Thiol-ester_cl (PF10569)

Summary: Alpha-macro-globulin thiol-ester bond-forming region

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Alpha-macro-globulin thiol-ester bond-forming region Provide feedback

This short highly conserved region of proteinase-binding alpha-macro-globulins contains the cysteine and a glutamine of a thiol-ester bond that is cleaved at the moment of proteinase binding, and mediates the covalent binding of the alpha-macro-globulin to the proteinase. The GCGEQ motif is highly conserved.

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR019565

This entry contains serum complement C3 and C4 precursors and alpha-macrogrobulins.

The alpha-macroglobulin (aM) family of proteins includes protease inhibitors [PUBMED:2473064], typified by the human tetrameric a2-macroglobulin (a2M); they belong to the MEROPS proteinase inhibitor family I39, clan IL. These protease inhibitors share several defining properties, which include (i) the ability to inhibit proteases from all catalytic classes, (ii) the presence of a 'bait region' and a thiol ester, (iii) a similar protease inhibitory mechanism and (iv) the inactivation of the inhibitory capacity by reaction of the thiol ester with small primary amines. aM protease inhibitors inhibit by steric hindrance [PUBMED:2472396]. The mechanism involves protease cleavage of the bait region, a segment of the aM that is particularly susceptible to proteolytic cleavage, which initiates a conformational change such that the aM collapses about the protease. In the resulting aM-protease complex, the active site of the protease is sterically shielded, thus substantially decreasing access to protein substrates. Two additional events occur as a consequence of bait region cleavage, namely (i) the h-cysteinyl-g-glutamyl thiol ester becomes highly reactive and (ii) a major conformational change exposes a conserved COOH-terminal receptor binding domain [PUBMED:2469470] (RBD). RBD exposure allows the aM protease complex to bind to clearance receptors and be removed from circulation [PUBMED:2430968]. Tetrameric, dimeric, and, more recently, monomeric aM protease inhibitors have been identified [PUBMED:9914899, PUBMED:10426429].

This short highly conserved region of proteinase-binding alpha-macro-globulins contains the cysteine and a glutamine of a thiol-ester bond that is cleaved at the moment of proteinase binding, and mediates the covalent binding of the alpha-macro-globulin to the proteinase. The GCGEQ motif is highly conserved.

Domain organisation

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

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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...

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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
(83)
Full
(1638)
Representative proteomes NCBI
(1531)
Meta
(44)
RP15
(121)
RP35
(201)
RP55
(399)
RP75
(611)
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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
(83)
Full
(1638)
Representative proteomes NCBI
(1531)
Meta
(44)
RP15
(121)
RP35
(201)
RP55
(399)
RP75
(611)
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
(83)
Full
(1638)
Representative proteomes NCBI
(1531)
Meta
(44)
RP15
(121)
RP35
(201)
RP55
(399)
RP75
(611)
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: PROSITE_PS00477
Previous IDs: none
Type: Domain
Author: Finn R, Coggill P
Number in seed: 83
Number in full: 1638
Average length of the domain: 29.30 aa
Average identity of full alignment: 44 %
Average coverage of the sequence by the domain: 2.09 %

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 20.1 20.1
Trusted cut-off 20.1 20.1
Noise cut-off 19.9 20.0
Model length: 31
Family (HMM) version: 4
Download: download the raw HMM for this family

Species distribution

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Interactions

There are 3 interactions for this family. More...

A2M_comp A2M_recep Thiol-ester_cl

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 Thiol-ester_cl domain has been found. There are 55 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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