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3  structures 54  species 1  interaction 94  sequences 6  architectures

Family: MHCassoc_trimer (PF08831)

Summary: Class II MHC-associated invariant chain trimerisation domain

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Class II MHC-associated invariant chain trimerisation domain Provide feedback

The class II associated invariant chain peptide is required for folding and localisation of MHC class II heterodimers. This domain is involved in trimerisation of the ectoderm and interferes with DM/class II binding. The trimeric protein forms a cylindrical shape which is thought to be important for interactions between the invariant chain and class II molecules [1].

Literature references

  1. Jasanoff A, Wagner G, Wiley DC; , EMBO J. 1998;17:6812-6818.: Structure of a trimeric domain of the MHC class II-associated chaperonin and targeting protein Ii. PUBMED:9843486 EPMC:9843486


External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR011988

This entry represents the trimerisation domain of the MHC class II-associated invariant chain (Ii). Ii plays a critical role in the assembly of the MHC, as well as in MHC II antigen processing by stabilising peptide-free class II alpha/beta heterodimers in a complex soon after their synthesis and directing transport of the complex from the endoplasmic reticulum to compartments where peptide loading of class II takes place [PUBMED:16337363]. In antigen-presenting cells (APCs), loading of MHC II molecules with peptides is regulated by Ii, which blocks MHC II antigen-binding sites in pre-endosomal compartments [PUBMED:16181341]. Several molecules then act upon MHC II molecules in endosomes to facilitate peptide loading: Ii-degrading proteases, the peptide exchange factor, human leukocyte antigen-DM (HLA-DM), and its modulator, HLA-DO (DO).

The Invariant chain contains a single transmembrane domain. Ii first assembles into a trimer and then associates with three class II alpha/beta MHC heterodimers. Although the membrane-proximal region of the Ii luminal domain is structurally disordered, the C-terminal segment of the luminal domain is largely alpha-helical and contains a major interaction site for the Ii trimer [PUBMED:9843486].

More information about these proteins can be found at Protein of the Month: MHC [PUBMED:].

Gene Ontology

The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.

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
(10)
Full
(94)
Representative proteomes NCBI
(80)
Meta
(0)
RP15
(1)
RP35
(2)
RP55
(11)
RP75
(27)
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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
(10)
Full
(94)
Representative proteomes NCBI
(80)
Meta
(0)
RP15
(1)
RP35
(2)
RP55
(11)
RP75
(27)
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
(10)
Full
(94)
Representative proteomes NCBI
(80)
Meta
(0)
RP15
(1)
RP35
(2)
RP55
(11)
RP75
(27)
Raw Stockholm Download   Download   Download   Download   Download   Download   Download    
Gzipped 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.

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: pdb_1iie
Previous IDs: none
Type: Domain
Author: Mistry J
Number in seed: 10
Number in full: 94
Average length of the domain: 70.80 aa
Average identity of full alignment: 51 %
Average coverage of the sequence by the domain: 27.02 %

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 55.0 55.0
Noise cut-off 21.5 18.5
Model length: 72
Family (HMM) version: 5
Download: download the raw HMM for this family

Species distribution

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Interactions

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

MHCassoc_trimer

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 MHCassoc_trimer domain has been found. There are 3 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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