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2252  structures 494  species 0  interactions 91542  sequences 1245  architectures

Family: V-set (PF07686)

Summary: Immunoglobulin V-set domain

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This is the Wikipedia entry entitled "Immunoglobulin V-set domain". More...

Immunoglobulin V-set domain Edit Wikipedia article

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

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.

Immunoglobulin V-set domain Provide feedback

This domain is found in antibodies as well as neural protein P0 and CTL4 amongst others.

Internal database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR013106

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 V-set domains, which are Ig-like domains resembling the antibody variable domain. V-set domains are found in diverse protein families, including immunoglobulin light and heavy chains; in several T-cell receptors such as CD2 (Cluster of Differentiation 2), CD4, CD80, and CD86; in myelin membrane adhesion molecules; in junction adhesion molecules (JAM); in tyrosine-protein kinase receptors; and in the programmed cell death protein 1 (PD1).

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 Ig (CL0011), which has the following description:

Members of the immunoglobulin superfamily are found in hundreds of proteins of different functions. Examples include antibodies, the giant muscle kinase titin and receptor tyrosine kinases. Immunoglobulin-like domains may be involved in protein-protein and protein-ligand interactions. The superfamily can be divided into discrete structural sets, by the presence or absence of beta-strands in the structure and the length of the domains [1]. Proteins containing domains of the C1 and V-sets are mostly molecules of the vertebrate immune system. Proteins of the C2-set are mainly lymphocyte antigens, this differs from the composition of the C2-set as originally proposed [1]. The I-set is intermediate in structure between the C1 and V-sets and is found widely in cell surface proteins as well as intracellular muscle proteins.

The clan contains the following 34 members:

Adeno_E3_CR1 Adhes-Ig_like bCoV_NS7A bCoV_NS8 C1-set C2-set C2-set_2 CD4-extracel DUF1968 Herpes_gE Herpes_gI Herpes_glycop_D I-set ICAM_N ig Ig_2 Ig_3 Ig_4 Ig_5 Ig_6 Ig_7 Ig_C17orf99 Ig_C19orf38 Ig_Tie2_1 Izumo-Ig K1 Marek_A ObR_Ig PTCRA Receptor_2B4 UL141 V-set V-set_2 V-set_CD47


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 (reference proteomes) using the family HMM. We also generate alignments using four representative proteomes (RP) sets and the UniProtKB 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.

Representative proteomes UniProt
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PP/heatmap 1            

1Cannot generate PP/Heatmap alignments for seeds; no PP data available

Key: ✓ available, x not generated, not available.

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Representative proteomes UniProt

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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.

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

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...


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: Bateman A
Previous IDs: none
Type: Domain
Sequence Ontology: SO:0000417
Author: Bateman A
Number in seed: 58
Number in full: 91542
Average length of the domain: 105.10 aa
Average identity of full alignment: 17 %
Average coverage of the sequence by the domain: 35.02 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 61295632 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 26.0 26.0
Trusted cut-off 26.0 26.0
Noise cut-off 25.9 25.9
Model length: 109
Family (HMM) version: 20
Download: download the raw HMM for this family

Species distribution

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Colour assignments

Archea Archea Eukaryota Eukaryota
Bacteria Bacteria Other sequences Other sequences
Viruses Viruses Unclassified Unclassified
Viroids Viroids Unclassified sequence Unclassified sequence


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


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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 V-set domain has been found. There are 2252 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 sequence.

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AlphaFold Structure Predictions

The list of proteins below match this family and have AlphaFold predicted structures. Click on the protein accession to view the predicted structure.

Protein Predicted structure External Information
A0A075B5I2 View 3D Structure Click here
A0A075B5I3 View 3D Structure Click here
A0A075B5I8 View 3D Structure Click here
A0A075B5I9 View 3D Structure Click here
A0A075B5J0 View 3D Structure Click here
A0A075B5J2 View 3D Structure Click here
A0A075B5J5 View 3D Structure Click here
A0A075B5J6 View 3D Structure Click here
A0A075B5J7 View 3D Structure Click here
A0A075B5J9 View 3D Structure Click here
A0A075B5K0 View 3D Structure Click here
A0A075B5K2 View 3D Structure Click here
A0A075B5K3 View 3D Structure Click here
A0A075B5K6 View 3D Structure Click here
A0A075B5K7 View 3D Structure Click here
A0A075B5K8 View 3D Structure Click here
A0A075B5K9 View 3D Structure Click here
A0A075B5L0 View 3D Structure Click here
A0A075B5L1 View 3D Structure Click here
A0A075B5L2 View 3D Structure Click here
A0A075B5L3 View 3D Structure Click here
A0A075B5L4 View 3D Structure Click here
A0A075B5L5 View 3D Structure Click here
A0A075B5L6 View 3D Structure Click here
A0A075B5L7 View 3D Structure Click here
A0A075B5L8 View 3D Structure Click here
A0A075B5M1 View 3D Structure Click here
A0A075B5M2 View 3D Structure Click here
A0A075B5M3 View 3D Structure Click here
A0A075B5M4 View 3D Structure Click here
A0A075B5M7 View 3D Structure Click here
A0A075B5M8 View 3D Structure Click here
A0A075B5M9 View 3D Structure Click here
A0A075B5N0 View 3D Structure Click here
A0A075B5N2 View 3D Structure Click here
A0A075B5N3 View 3D Structure Click here
A0A075B5N4 View 3D Structure Click here
A0A075B5N5 View 3D Structure Click here
A0A075B5N6 View 3D Structure Click here
A0A075B5N7 View 3D Structure Click here