Summary: CD80-like C2-set immunoglobulin domain

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Wikipedia: Immunoglobulin C2-set domain
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Immunoglobulin C2-set domain

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Immunoglobulin C2-set domain

Identifiers

Symbol

C2-set

Available protein structures:
Pfam	structures
PDB	RCSB PDB; PDBe
PDBsum	structure summary

The basic structure of immunoglobulin (Ig) molecules is a tetramer of two light chains and two heavy chains linked by disulphide bonds. There are two types of light chains: kappa and lambda, each composed of a constant domain (CL) and a variable domain (VL). There are five types of heavy chains: alpha, delta, epsilon, gamma and mu, all consisting of a variable domain (VH) and three (in alpha, delta and gamma) or four (in epsilon and mu) constant domains (CH1 to CH4). Ig molecules are highly modular proteins, in which the variable and constant domains have clear, conserved sequence patterns. The domains in Ig and Ig-like molecules are grouped into four types: V-set (variable; IPR013106), C1-set (constant-1; IPR003597), C2-set (constant-2; IPR008424) and I-set (intermediate; IPR013098).^[1] Structural studies have shown that these domains share a common core Greek-key beta-sandwich structure, with the types differing in the number of strands in the beta-sheets as well as in their sequence patterns.^[2]^[3]

Immunoglobulin-like domains that are related in both sequence and structure can be found in several diverse protein families. Ig-like domains are involved in a variety of functions, including cell–cell recognition, cell-surface receptors, muscle structure and the immune system.^[4]

C2-set domains, which are Ig-like domains resembling the antibody constant domain. C2-set domains are found primarily in the mammalian T-cell surface antigens CD2 (Cluster of Differentiation 2), CD4 and CD80, as well as in vascular (VCAM) and intercellular (ICAM) cell adhesion molecules.

CD2 mediates T-cell adhesion via its ectodomain, and signal transduction utilising its 117-amino acid cytoplasmic tail.^[5] CD2 displays structural and functional similarities with African swine fever virus (ASFV) LMW8-DR, a protein that is involved in cell–cell adhesion and immune response modulation, suggesting a possible role in the pathogenesis of ASFV infection.^[6] CD4 is the primary receptor for HIV-1. CD4 has four immunoglobulin-like domains in its extracellular region that share the same structure, but can differ in sequence. Certain extracellular domains may be involved in dimerisation.^[7]

[edit] References

^ Smith DK, Xue H (1997). "Sequence profiles of immunoglobulin and immunoglobulin-like domains". J. Mol. Biol. 274 (4): 530–545. doi:10.1006/jmbi.1997.1432. PMID 9417933.
^ Potapov V, Sobolev V, Edelman M, Kister A, Gelfand I (2004). "Protein-Protein Recognition: Juxtaposition of Domain and Interface Cores in Immunoglobulins and Other Sandwich-like Proteins". J. Mol. Biol. 342 (2): 665–679. doi:10.1016/j.jmb.2004.06.072. PMID 15327963.
^ Clarke J, Fowler SB (2001). "Mapping the folding pathway of an immunoglobulin domain: structural detail from Phi value analysis and movement of the transition state". Structure 9 (5): 355–366. doi:10.1016/S0969-2126(01)00596-2. PMID 11377196.
^ Chothia C, Teichmann SA (2000). "Immunoglobulin superfamily proteins in Caenorhabditis elegans". J. Mol. Biol. 296 (5): -. doi:10.1006/jmbi.1999.3497. PMID 10698639.
^ Reinherz EL, Yang H (2001). "Dynamic recruitment of human CD2 into lipid rafts. Linkage to T cell signal transduction". J. Biol. Chem. 276 (22): 18775–18785. doi:10.1074/jbc.M009852200. PMID 11376005.
^ Kutish GF, Rock DL, Afonso CL, Borca MV, Irusta P, Carrillo C, Brun A, Sussman M (1994). "An African swine fever virus gene with similarity to the T-lymphocyte surface antigen CD2 mediates hemadsorption". Virology 199 (2): 463–468. doi:10.1006/viro.1994.1146. PMID 7907198.
^ Sanejouand YH (2004). "Domain swapping of CD4 upon dimerization". Proteins 57 (1): -. doi:10.1002/prot.20197. PMID 15326605.

[edit] Human proteins containing this domain

CD2; CD4; VCAM1;

[edit] References

This article incorporates text from the public domain Pfam and InterPro IPR008424

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CD80-like C2-set immunoglobulin domain

These domains belong to the immunoglobulin superfamily.

Clan

This family is a member of clan Ig (CL0011), which has a total of 22 members.

External database links

PANDIT:	PF08205
Pseudofam:	PF08205
SCOP:	1dr9
SYSTERS:	C2-set_2

This tab holds annotation information from the InterPro database.

InterPro entry IPR013162

The basic structure of immunoglobulin (Ig) molecules is a tetramer of two light chains and two heavy chains linked by disulphide bonds. There are two types of light chains: kappa and lambda, each composed of a constant domain (CL) and a variable domain (VL). There are five types of heavy chains: alpha, delta, epsilon, gamma and mu, all consisting of a variable domain (VH) and three (in alpha, delta and gamma) or four (in epsilon and mu) constant domains (CH1 to CH4). Ig molecules are highly modular proteins, in which the variable and constant domains have clear, conserved sequence patterns. The domains in Ig and Ig-like molecules are grouped into four types: V-set (variable; INTERPRO), C1-set (constant-1; INTERPRO), C2-set (constant-2; INTERPRO) and I-set (intermediate; INTERPRO) [PUBMED:9417933]. Structural studies have shown that these domains share a common core Greek-key beta-sandwich structure, with the types differing in the number of strands in the beta-sheets as well as in their sequence patterns [PUBMED:15327963, PUBMED:11377196].

Immunoglobulin-like domains that are related in both sequence and structure can be found in several diverse protein families. Ig-like domains are involved in a variety of functions, including cell-cell recognition, cell-surface receptors, muscle structure and the immune system [PUBMED:10698639].

This entry represents the C2-set type domains found in the T-cell antigen CD80, as well as in related proteins. CD80 (B7-1) is a glycoprotein expressed on antigen-presenting cells [PUBMED:10661405]. The shared ligands on CD80 and CD86 (B7-2) deliver the co-stimulatory signal through CD28 and CTLA-4 on T-cells, where CD28 augments the T-cell response and CTLA-4 attenuates it [PUBMED:11279502].

Domain organisation

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

Loading domain graphics...

Pfam Clan

This family is a member of clan Ig (CL0011), which contains the following 22 members:

A2M Adeno_E3_CR1 Adhes-Ig_like C1-set C2-set C2-set_2 Herpes_gE Herpes_gI Herpes_glycop_D I-set ICAM_N ig Ig_2 Ig_3 Ig_Tie2_1 K1 Lep_receptor_Ig Marek_A Receptor_2B4 SVA V-set V-set_CD47

Alignments

There are various ways to view or download the sequence alignments that we store. You can use a sequence viewer to look at either the seed or full alignment for the family, or you can look at a plain text version of the sequence in a variety of different formats. More...

View options

Alignment:	Seed (33) Full (1860) NCBI (8449) Metagenomics (2)
Viewer:

Formatting options

Alignment:	Seed (33) Full (1860)
Format:
Order:	Tree Alphabetical
Sequence:	Inserts lower case All upper case
Gaps:
Download/view:	Download View

Download options

Very large alignments can often cause problems for the formatting tool above. If you find that downloading or viewing a large alignment is problematic, you can also download a gzip-compressed, Stockholm-format file containing the seed or full alignment for this family.

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

The main seed and full alignments are generated using sequences from the UniProt sequence database. However, we also generate alignments using sequences from the NCBI sequence database and the "metaseq" metagenomics dataset.

You can view alignments from these two additional datasets using the form above, or you can download alignments of NCBI or metagenomics sequences, as gzip-compressed files.

Pfam alignments:	Seed (33) Full (1860) NCBI (8449) Metagenomics (2)
Full length sequences	Full-sequences (1860)

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. 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 or full alignments.

Note: You can also download the data files for the seed, full, NCBI or metagenomics trees.

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

Seed source:

Pfam-B_280 (release 17.0)

Previous IDs:

none

Type:

Domain

Author:

Bateman A

Number in seed:

33

Number in full:

1860

Average length of the domain:

86.40 aa

Average identity of full alignment:

17 %

Average coverage of the sequence by the domain:

14.26 %

HMM information

HMM build commands:

build method: hmmbuild -o /dev/null HMM SEED

search method: hmmsearch -Z 15929002 -E 1000 --cpu 4 HMM pfamseq

Model details:

Parameter	Sequence	Domain
Gathering cut-off	20.8	20.8
Trusted cut-off	20.8	20.8
Noise cut-off	20.7	20.7

Model length:

89

Family (HMM) version:

7

Download:

download the raw HMM for this family

Species distribution

Sunburst
Tree

Sunburst controls

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Weight segments by...

number of sequences
number of species

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Colour assignments

Archea	Eukaryota
Bacteria	Other sequences
Viruses	Unclassified
Viroids	Unclassified sequence

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 if you need to select sub-trees and view sequence alignments. More...

This chart is a modified "sunburst" visualisation of the species tree for this family. It shows each node in the tree as a separate arc, arranged radially with the superkingdoms at the centre and the species arrayed around the outermost ring.

How the sunburst is generated

The tree is built by considering the taxonomic lineage of each sequence that has a match to this family. For each node in the resulting tree, we draw an arc in the sunburst. The radius of the arc, it's distance from the root node at the centre of the sunburst, shows the taxonomic level ("superkingdom", "kingdom", etc). The length of the arc represents either the number of sequences represented at a given level, or the number of species that are found beneath the node in the tree. The weighting scheme can be changed using the sunburst controls.

In order to reduce the complexity of the representation, we reduce the number of taxonomic levels that we show. We consider only the following eight major taxonomic levels:

superkingdom
kingdom
phylum
class
order
family
genus
species

Colouring and labels

Segments of the tree are coloured approximately according to their superkingdom. For example, archeal branches are coloured with shades of orange, eukaryotes in shades of purple, etc. The colour assignments are shown under the sunburst controls. Where space allows, the name of the taxonomic level will be written on the arc itself.

As you move your mouse across the sunburst, the current node will be highlighted. In the top section of the controls panel we show a summary of the lineage of the currently highlighed node. If you pause over an arc, a tooltip will be shown, giving the name of the taxonomic level in the title and a summary of the number of sequences and species below that node in the tree.

Anomalies in the taxonomy tree

There are some situations that the sunburst tree cannot easily handle and for which we have work-arounds in place.

Missing taxonomic levels

Some species in the taxonomic tree may not have one or more of the main eight levels that we display. For example, Bos taurus is not assigned an order in the NCBI taxonomic tree. In such cases we mark the omitted level with, for example, "No order", in both the tooltip and the lineage summary.

Unmapped species names

The tree is built by looking at each sequence in the full alignment for the family. We take the name of the species given by UniProt and try to map that to the full taxonomic tree from NCBI. In some cases, the name chosen by UniProt does not map to any node in the NCBI tree, perhaps because the chosen name is listed as a synonym or a misspelling in the NCBI taxonomy.

So that these nodes are not simply omitted from the sunburst tree, we group them together in a separate branch (or segment of the sunburst tree). Since we cannot determine the lineage for these unmapped species, we show all levels between the superkingdom and the species as "uncategorised".

Sub-species

Since we reduce the species tree to only the eight main taxonomic levels, sequences that are mapped to the sub-species level in the tree would not normally be shown. Rather than leave out these species, we map them instead to their parent species. So, for example, for sequences belonging to one of the Vibrio cholerae sub-species in the NCBI taxonomy, we show them instead as belonging to the species Vibrio cholerae.

Too many species/sequences

For large species trees, you may see blank regions in the outer layers of the sunburst. These occur when there are large numbers of arcs to be drawn in a small space. If an arc is less than approximately one pixel wide, it will not be drawn and the space will be left blank. You may still be able to get some information about the species in that region by moving your mouse across the area, but since each arc will be very small, it will be difficult to accurately locate a particular species.

Tree controls

Hide

The tree shows the occurrence of this domain across different species. More...

Species trees

We show the species tree in one of two ways. For smaller trees we try to show an interactive representation, which allows you to select specific nodes in the tree and view them as an alignment or as a set of Pfam domain graphics.

Unfortunately we have found that there are problems viewing the interactive tree when the it becomes larger than a certain limit. Furthermore, we have found that Internet Explorer can become unresponsive when viewing some trees, regardless of their size. We therefore show a text representation of the species tree when the size is above a certain limit or if you are using Internet Explorer to view the site.

If you are using IE you can still load the interactive tree by clicking the "Generate interactive tree" button, but please be aware of the potential problems that the interactive species tree can cause.

Interactive tree

For all of the domain matches in a full alignment, we count the number that are found on all sequences in the alignment. This total is shown in the purple box.

We also count the number of unique sequences on which each domain is found, which is shown in green. Note that a domain may appear multiple times on the same sequence, leading to the difference between these two numbers.

Finally, we group sequences from the same organism according to the NCBI code that is assigned by UniProt, allowing us to count the number of distinct sequences on which the domain is found. This value is shown in the pink boxes.

We use the NCBI species tree to group organisms according to their taxonomy and this forms the structure of the displayed tree. Note that in some cases the trees are too large (have too many nodes) to allow us to build an interactive tree, but in most cases you can still view the tree in a plain text, non-interactive representation. Those species which are represented in the seed alignment for this domain are highlighted.

You can use the tree controls to manipulate how the interactive tree is displayed:

show/hide the summary boxes
highlight species that are represented in the seed alignment
expand/collapse the tree or expand it to a given depth
select a sub-tree or a set of species within the tree and view them graphically or as an alignment
save a plain text representation of the tree

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Please note: for large trees this can take some time. While the tree is loading, you can safely switch away from this tab but if you browse away from the family page entirely, the tree will not be loaded.

Interactions

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

V-set

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 C2-set_2 domain has been found. There are 4 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.

Loading structure mapping...

Family: C2-set_2 (PF08205)

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Summary: CD80-like C2-set immunoglobulin domain

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Contact us

Immunoglobulin C2-set domain

[edit] References

[edit] Human proteins containing this domain

[edit] References

CD80-like C2-set immunoglobulin domain

Clan

External database links

InterPro entry IPR013162

Domain organisation

Pfam Clan

Alignments

Viewing

Downloading

View options

Formatting options

Download options

External links

HMM logo

Trees

Curation and family details

Curation

HMM information

Species distribution

Sunburst controls

Weight segments by...

Change the size of the sunburst

Colour assignments

How the sunburst is generated

Colouring and labels

Anomalies in the taxonomy tree

Missing taxonomic levels

Unmapped species names

Sub-species

Too many species/sequences

Tree controls

Annotation

Download tree

Selected sequences

Species trees

Interactive tree

Interactions

Structures