Summary: SH2 domain
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SH2 domain Edit Wikipedia article
The SH2 (Src Homology 2) domain is a structurally conserved protein domain contained within the Src oncoprotein and in many other intracellular signal-transducing proteins. SH2 domains allow proteins containing those domains to dock to phosphorylated tyrosine residues on other proteins. SH2 domains are commonly found in adapter proteins that aid in the signal transduction of receptor tyrosine kinase pathways.
Protein-protein interactions play a major role in cellular growth and development. Modular domains, which are the subunits of a protein, moderate these protein interactions by identifying short peptide sequences. These peptide sequences determine the binding partners of each protein. One of the more prominent domains is the SH2 domain. SH2 domains play a vital role in cellular communication. Its length is approximately 100 amino acids long and it is found within 111 human proteins. Regarding its structure, it contains 2 alpha helices and 7 beta strands. Research has shown that it has a high affinity to phosphorylated tyrosine residues and it is known to identify a sequence of 3-6 amino acids within a peptide motif.
Binding and phosphorylation
SH2 domains typically bind a phosphorylated tyrosine residue in the context of a longer peptide motif within a target protein, and SH2 domains represent the largest class of known pTyr-recognition domains.
Phosphorylation of tyrosine residues in a protein occurs during signal transduction and is carried out by tyrosine kinases. In this way, phosphorylation of a substrate by tyrosine kinases acts as a switch to trigger binding to an SH2 domain-containing protein. Many tyrosine containing short linear motifs that bind to SH2 domains are conserved across a wide variety of higher Eukaryotes.  The intimate relationship between tyrosine kinases and SH2 domains is supported by their coordinate emergence during eukaryotic evolution.
A detailed bioinformatic examination of SH2 domains of human and mouse reveals 120 SH2 domains contained within 115 proteins encoded by the human genome, representing a rapid rate of evolutionary expansion among the SH2 domains.
A large number of SH2 domain structures have been solved and many SH2 proteins have been knocked out in mice. Information generated on the Mouse Knockouts can be found on the sh2.uchicago.edu website.
The function of SH2 domains is to specifically recognize the phosphorylated state of tyrosine residues, thereby allowing SH2 domain-containing proteins to localize to tyrosine-phosphorylated sites. This process constitutes the fundamental event of signal transduction through a membrane, in which a signal in the extracellular compartment is "sensed" by a receptor and is converted in the intracellular compartment to a different chemical form, i.e. that of a phosphorylated tyrosine. Tyrosine phosphorylation leads to activation of a cascade of protein-protein interactions whereby SH2 domain-containing proteins are recruited to tyrosine-phosphorylated sites. This process initiates a series of events which eventually result in altered patterns of gene expression or other cellular responses. The SH2 domain, which was first identified in the oncoproteins Src and Fps, is about 100 amino-acid residues long. It functions as a regulatory module of intracellular signaling cascades by interacting with high affinity to phosphotyrosine-containing target peptides in a sequence-specific and strictly phosphorylation-dependent manner.
Human proteins containing this domain include:
- ABL1; ABL2
- BCAR3; BLK; BLNK; BMX; BTK
- CHN2; CISH; CRK; CRKL; CSK
- FER; FES; FGR; FRK; FYN
- GRAP; GRAP2; GRB10; GRB14; GRB2; GRB7
- HCK; HSH2D
- INPP5D; INPPL1; ITK; JAK2; LCK; LCP2; LYN
- MATK; NCK1; NCK2
- PIK3R1; PIK3R2; PIK3R3; PLCG1; PLCG2; PTK6; PTPN11; PTPN6; RASA1
- SH2B1; SH2B2; SH2B3; SH2D1A; SH2D1B; SH2D2A; SH2D3A; SH2D3C; SH2D4A; SH2D4B; SH2D5; SH2D6; SH3BP2; SHB; SHC1; SHC3; SHC4; SHD; SHE
- SLA; SLA2
- SOCS1; SOCS2; SOCS3; SOCS4; SOCS5; SOCS6; SOCS7
- SRC; SRMS
- STAT1; STAT2; STAT3; STAT4; STAT5A; STAT5B; STAT6
- SUPT6H; SYK
- TEC; TENC1; TNS; TNS1; TNS3; TNS4; TXK
- VAV1; VAV2; VAV3
- YES1; ZAP70
- PDB 1lkk; Tong L, Warren TC, King J, Betageri R, Rose J, Jakes S (March 1996). "Crystal structures of the human p56lck SH2 domain in complex with two short phosphotyrosyl peptides at 1.0 A and 1.8 A resolution". J. Mol. Biol. 256 (3): 601â10. doi:10.1006/jmbi.1996.0112. PMID 8604142.
- Sadowski I, Stone JC, Pawson T (December 1986). "A noncatalytic domain conserved among cytoplasmic protein-tyrosine kinases modifies the kinase function and transforming activity of Fujinami sarcoma virus P130gag-fps". Mol. Cell. Biol. 6 (12): 4396â408. PMC 367222. PMID 3025655.
- Russell RB, Breed J, Barton GJ (June 1992). "Conservation analysis and structure prediction of the SH2 family of phosphotyrosine binding domains". FEBS Lett. 304 (1): 15â20. doi:10.1016/0014-5793(92)80579-6. PMID 1377638.
- Koytiger G, Kaushansky A, Gordus A, Rush J, Sorger PK, Macbeath G (January 2013). "Phosphotyrosine signaling proteins that drive oncogenesis tend to be highly interconnected". Mol. Cell Proteomics. doi:10.1074/mcp.M112.025858. PMID 23358503.
- Liu, B. A.; Shah, E.; Jablonowski, K.; Stergachis, A.; Engelmann, B.; Nash, P. D. (2011). "The SH2 Domain-Containing Proteins in 21 Species Establish the Provenance and Scope of Phosphotyrosine Signaling in Eukaryotes". Science Signaling 4 (202): ra83. doi:10.1126/scisignal.2002105. PMID 22155787.
- Pawson T, Gish GD, Nash P (December 2001). "SH2 domains, interaction modules and cellular wiring". Trends in Cell Biology 11 (12): 504â11. doi:10.1016/S0962-8924(01)02154-7. PMID 11719057.
- Huang H, Li L, Wu C, Schibli D, Colwill K, Ma S, Li C, Roy P, Ho K, Songyang Z, Pawson T, Gao Y, Li SS (April 2008). "Defining the specificity space of the human SRC homology 2 domain". Molecular & Cellular Proteomics : MCP 7 (4): 768â84. doi:10.1074/mcp.M700312-MCP200. PMID 17956856.
- Ren, S.; Yang, G.; He, Y.; Wang, Y.; Li, Y.; Chen, Z. (2008). "The conservation pattern of short linear motifs is highly correlated with the function of interacting protein domains". BMC Genomics 9: 452. doi:10.1186/1471-2164-9-452. PMC 2576256. PMID 18828911.
- Eichinger L, Pachebat JA, GlÃ¶ckner G, et al. (May 2005). "The genome of the social amoeba Dictyostelium discoideum". Nature 435 (7038): 43â57. doi:10.1038/nature03481. PMC 1352341. PMID 15875012.
- Liu BA, Jablonowski K, Raina M, ArcÃ© M, Pawson T, Nash PD (June 2006). "The human and mouse complement of SH2 domain proteins-establishing the boundaries of phosphotyrosine signaling". Molecular Cell 22 (6): 851â68. doi:10.1016/j.molcel.2006.06.001. PMID 16793553.
- Nash P, Pawson T, Jablonowski K. "the SH2 domain". The University of Chicago. Retrieved 2008-11-08.
- Eukaryotic Linear Motif resource motif class LIG_SH2_GRB2
- Eukaryotic Linear Motif resource motif class LIG_SH2_PTP2
- Eukaryotic Linear Motif resource motif class LIG_SH2_SRC
- Eukaryotic Linear Motif resource motif class LIG_SH2_STAT3
- Eukaryotic Linear Motif resource motif class LIG_SH2_STAT5
- Eukaryotic Linear Motif resource motif class LIG_SH2_STAT6
- Eukaryotic Linear Motif resource motif class MOD_TYR_ITAM
- Eukaryotic Linear Motif resource motif class MOD_TYR_ITIM
- Eukaryotic Linear Motif resource motif class MOD_TYR_ITSM
- Li S (2007). "SMALI site". University of Western Ontario. Retrieved 2009-01-08.
- Mayer BJ (2007-10-23). "SH2 Domain Database link page". University of Connecticut. Retrieved 2009-01-08.[dead link]
- The Nash Lab (2005). "the SH2 domain". The Nash Lab. Retrieved 2012-12-13.
- The Pawson Lab. "SH2 Domain". Mount Sinai Hospital, Ontario, Canada. Retrieved 2009-01-08.
- Rose T, Waksman G (2000-02-29). "SH2 domains: Introduction and Overview". Washington University School of Medicine. Retrieved 2009-01-08.
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Internal database links
|Similarity to PfamA using HHSearch:||SH2_2|
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR000980
The Src homology 2 (SH2) domain is a protein domain of about 100 amino-acid residues first identified as a conserved sequence region between the oncoproteins Src and Fps [PUBMED:3025655]. Similar sequences were later found in many other intracellular signal-transducing proteins [PUBMED:1377638]. SH2 domains function as regulatory modules of intracellular signalling cascades by interacting with high affinity to phosphotyrosine-containing target peptides in a sequence-specific, SH2 domains recognise between 3-6 residues C-terminal to the phosphorylated tyrosine in a fashion that differs from one SH2 domain to another, and strictly phosphorylation-dependent manner [PUBMED:7883800, PUBMED:15335710, PUBMED:14731533, PUBMED:7531822]. They are found in a wide variety of protein contexts e.g., in association with catalytic domains of phospholipase Cy (PLCy) and the non-receptor protein tyrosine kinases; within structural proteins such as fodrin and tensin; and in a group of small adaptor molecules, i.e Crk and Nck. The domains are frequently found as repeats in a single protein sequence and will then often bind both mono- and di-phosphorylated substrates.
The structure of the SH2 domain belongs to the alpha+beta class, its overall shape forming a compact flattened hemisphere. The core structural elements comprise a central hydrophobic anti-parallel beta-sheet, flanked by 2 short alpha-helices. The loop between strands 2 and 3 provides many of the binding interactions with the phosphate group of its phosphopeptide ligand, and is hence designated the phosphate binding loop, the phosphorylated ligand binds perpendicular to the beta-sheet and typically interacts with the phosphate binding loop and a hydrophobic binding pocket that interacts with a pY+3 side chain. The N- and C-termini of the domain are close together in space and on the opposite face from the phosphopeptide binding surface and it has been speculated that this has facilitated their integration into surface-exposed regions of host proteins [PUBMED:11911873].
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Molecular function||protein binding (GO:0005515)|
Below is a listing of the unique domain organisations or architectures in which this domain is found. More...
The graphic that is shown by default represents the longest sequence with a given architecture. Each row contains the following information:
- 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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Note that you can see the family page for a particular domain by clicking on the graphic. You can also choose to see all sequences which have a given architecture by clicking on the Show link in each row.
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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...
There are various ways to view or download the sequence alignments that we store. We provide several sequence viewers and a plain-text Stockholm-format file for download.
We make a range of alignments for each Pfam-A family:
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- 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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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.
1Cannot generate PP/Heatmap alignments for seeds; no PP data available
Key: available, not generated, — not available.
Format an alignment
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.
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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.
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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.
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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.
|Number in seed:||58|
|Number in full:||9081|
|Average length of the domain:||78.00 aa|
|Average identity of full alignment:||27 %|
|Average coverage of the sequence by the domain:||14.81 %|
|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:||19|
|Download:||download the raw HMM for this family|
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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 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, its 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:
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".
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.
The tree shows the occurrence of this domain across different species. More...
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.
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
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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.
There are 8 interactions for this family. More...
We determine these interactions using iPfam, which considers the interactions between residues in three-dimensional protein structures and maps those interactions back to Pfam families. You can find more information about the iPfam algorithm in the journal article that accompanies the website.
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 SH2 domain has been found. There are 390 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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