Summary: Phycoerythrin, alpha/beta chain
Pfam includes annotations and additional family information from a range of different sources. These sources can be accessed via the tabs below.
This is the Wikipedia entry entitled "Phycoerythrin". More...
The Wikipedia text that you see displayed here is a download from Wikipedia. This means that the information we display is a copy of the information from the Wikipedia database. The button next to the article title ("Edit Wikipedia article") takes you to the edit page for the article directly within Wikipedia. You should be aware you are not editing our local copy of this information. Any changes that you make to the Wikipedia article will not be displayed here until we next download the article from Wikipedia. We currently download new content on a nightly basis.
Does Pfam agree with the content of the Wikipedia entry ?
Pfam has chosen to link families to Wikipedia articles. In some case we have created or edited these articles but in many other cases we have not made any direct contribution to the content of the article. The Wikipedia community does monitor edits to try to ensure that (a) the quality of article annotation increases, and (b) vandalism is very quickly dealt with. However, we would like to emphasise that Pfam does not curate the Wikipedia entries and we cannot guarantee the accuracy of the information on the Wikipedia page.
Editing Wikipedia articles
Before you edit for the first time
Wikipedia is a free, online encyclopedia. Although anyone can edit or contribute to an article, Wikipedia has some strong editing guidelines and policies, which promote the Wikipedia standard of style and etiquette. Your edits and contributions are more likely to be accepted (and remain) if they are in accordance with this policy.
You should take a few minutes to view the following pages:
How your contribution will be recorded
Anyone can edit a Wikipedia entry. You can do this either as a new user or you can register with Wikipedia and log on. When you click on the "Edit Wikipedia article" button, your browser will direct you to the edit page for this entry in Wikipedia. If you are a registered user and currently logged in, your changes will be recorded under your Wikipedia user name. However, if you are not a registered user or are not logged on, your changes will be logged under your computer's IP address. This has two main implications. Firstly, as a registered Wikipedia user your edits are more likely seen as valuable contribution (although all edits are open to community scrutiny regardless). Secondly, if you edit under an IP address you may be sharing this IP address with other users. If your IP address has previously been blocked (due to being flagged as a source of 'vandalism') your edits will also be blocked. You can find more information on this and creating a user account at Wikipedia.
If you have problems editing a particular page, contact us at email@example.com and we will try to help.
The community annotation is a new facility of the Pfam web site. If you have problems editing or experience problems with these pages please contact us.
Phycoerythrin Edit Wikipedia article
|Phycoerythrin, alpha/beta chain|
|SCOPe||1qgw / SUPFAM|
Phycoerythrin (PE) is a red protein-pigment complex from the light-harvesting phycobiliprotein family, present in red algae and cryptophytes, accessory to the main chlorophyll pigments responsible for photosynthesis.
Like all phycobiliproteins, it is composed of a protein part covalently binding chromophores called phycobilins. In the phycoerythrin family, the most known phycobilins are: phycoerythrobilin, the typical phycoerythrin acceptor chromophore, and sometimes phycourobilin. Phycoerythrins are composed of (Î±Î²) monomers, usually organised in a disk-shaped trimer (Î±Î²)3 or hexamer (Î±Î²)6 (second one is the functional unit of the antenna rods). These typical complexes also contain a third type of subunit, the Î³ chain.
Phycobiliproteins are part of huge light harvesting antennae protein complexes called phycobilisomes. In red algae they are anchored to the stromal side of thylakoid membranes of chloroplasts, whereas in cryptophytes phycobilisomes are reduced and (phycobiliprotein 545 PE545 molecules here) are densely packed inside the lumen of thylakoides. 
Phycoerythrin is an accessory pigment to the main chlorophyll pigments responsible for photosynthesis. The light energy is captured by phycoerythrin and is then passed on to the reaction centre chlorophyll pair, most of the time via the phycobiliproteins phycocyanin and allophycocyanin.
Phycoerythrins except phycoerythrin 545 (PE545) are composed of (Î±Î²) monomers assembled into disc-shaped (Î±Î²)6 hexamers or (Î±Î²)3 trimers with 32 or 3 symmetry and enclosing central channel. In phycobilisomes (PBS) each trimer or hexamer contains at least one linker protein located in central channel. B-phycoerythrin (B-PE) and R-phycoerythrin (R-PE) from red algae in addition to Î± and Î² chains have a third, Î³ subunit contributing both linker and light-harvesting functions, because it bears chromophores. 
R-phycoerythrin is predominantly produced by red algae. The protein is made up of at least three different subunits and varies according to the species of algae that produces it. The subunit structure of the most common R-PE is (Î±Î²)6Î³. The Î± subunit has two phycoerythrobilins (PEB), the Î² subunit has 2 or 3 PEBs and one phycourobilin (PUB), while the different gamma subunits are reported to have 3 PEB and 2 PUB (Î³1) or 1 or 2 PEB and 1 PUB (Î³2). The molecular weight of R-PE is 250,000 Daltons.
|Chromophore or other
|Bilins||8||10||10||10||Î± and Î²|
|- Phycoerythrobilin (PEB)||6||10||0 or 8||8||Î² (PE545)|
or Î± and Î²
|- 15,16-dihydrobiliverdin (DBV)||2||-||-||-||Î± (-3 and -2)|
|- Phycocyanobilin (CYC)||-||-||8 or 7 or 0||-||Î± and Î²|
|- Biliverdine IX alpha (BLA)||-||-||0 or 1||-||Î±|
|- Phycourobilin (PUB)||-||-||2||2||Î²|
|5-hydroxylysine (LYZ)||1 or 2||-||-||-||Î± (-3 or |
-3 and -2)
|N-methyl asparagine (MEN)||2||2||0 or 2||2||Î²|
|Sulfate ion SO42âˆ’ (SO4)||-||5 or 1||0 or 2||-||Î± or Î± and Î²|
|Chloride ion Clâˆ’ (CL)||1||-||-||-||Î²|
|Magnesium ion Mg2+ (MG)||2||-||-||-||Î±-3 and Î²|
|inspected PDB files||1XG0
The assumed biological molecule of phycoerythrin 545 (PE545) is (Î±Î²)2 or rather (α3β)(α2β). The numbers 2 and 3 after the Î± letters in second formula are part of chain names here, not their counts. The synonym cryptophytan name of Î±3 chain is Î±1 chain.
The largest assembly of B-phycoerythrin (B-PE) is (Î±Î²)3 trimer . However, preparations from red algae yield also (Î±Î²)6 hexamer . In case of R-phycoerythrin (R-PE) the largest assumed biological molecule here is (Î±Î²Î³)6, (αβγ)3(αβ)3 or (Î±Î²)6 dependently on publication, for other phycoerythrin types (Î±Î²)6. These Î³ chains from the Protein Data Bank are very small and consist only of three or six recognizable amino acids , whereas described at the beginning of this section linker Î³ chain is large (for example 277 amino acid long 33 kDa in case of Î³33 from red algae Aglaothamnion neglectum) . This is because the electron density of the gamma-polypeptide is mostly averaged out by its threefold crystallographic symmetry and only a few amino acids can be modeled .
For (Î±Î²Î³)6, (Î±Î²)6 or (αβγ)3(αβ)3 the values from the table should be simply multiplied by 3, (Î±Î²)3 contain intermediate numbers of non-protein molecules. (this non sequitur needs to be corrected)
In phycoerythrin PE545 above, one Î± chain (-2 or -3) binds one molecule of billin, in other examples it binds two molecules. The Î² chain always binds to three molecules. The small Î³ chain binds to none.
Two molecules of N-methyl asparagine are bound to the Î² chain, one 5-hydroxylysine to Î± (-3 or -2), one Mg2+ to Î±-3 and Î², one Clâˆ’ to Î², 1-2 molecules of SO42âˆ’ to Î± or Î².
Below is sample crystal structure of R-phycoerythrin from Protein Data Bank:
Absorption peaks in the visible light spectrum are measured at 495 and 545/566 nm, depending on the chromophores bound and the considered organism. A strong emission peak exists at 575 Â± 10 nm. (i.e., phycoerythrin absorbs slightly blue-green/yellowish light and emits slightly orange-yellow light.)
|Absorption maximum||565 nm|
|Additional Absorption peak||498 nm|
|Emission maximum||573 nm|
|Extinction Coefficient (Îµ)||1.96 x 106 Mâˆ’1cmâˆ’1|
|Quantum Yield (QY)||0.84|
|Brightness (Îµ x QY)||1.65 x 106 Mâˆ’1cmâˆ’1|
PEB and DBV bilins in PE545 absorb in the green spectral region too, with maxima at 545 and 569 nm respectively. The fluorescence emission maximum is at 580 nm. 
As mentioned above, phycoerythrin can be found in a variety of algal species . As such, there can be variation in the efficiency of absorbance and emission of light required for facilitation of photosynthesis. This could be a result of the depth in the water column that a specific alga typically resides and a consequent need for greater or less efficiency of the accessory pigments.
With advances in imaging and detection technology which can avoid rapid photobleaching, protein fluorophores have become a viable and powerful tool for researchers in fields such as microscopy, microarray analysis and Western blotting. In light of this, it may be beneficial for researchers to screen these variable R-phycoerythrins to determine which one is most appropriate for their particular application. Even a small increase in fluorescent efficiency could reduce background noise and lower the rate of false-negative results.
R-Phycoerythrin (also known as PE or R-PE) is useful in the laboratory as a fluorescence-based indicator for the presence of cyanobacteria and for labeling antibodies, most often for flow cytometry. Its use is limited in immunofluorescence microscopy due to its rapid photobleaching characteristics. There are also other types of phycoerythrins, such as B-Phycoerythrin, which have slightly different spectral properties. B-Phycoerythrin absorbs strongly at about 545 nm (slightly yellowish green) and emits strongly at 572 nm (yellow) instead and could be better suited for some instruments. B-Phycoerythrin may also be less "sticky" than R-Phycoerythrin and contributes less to background signal due to non-specific binding in certain applications. However, R-PE is much more commonly available as an antibody conjugate.
R-Phycoerythrin and B-Phycoerythrin are among the brightest fluorescent dyes ever identified.
- Ficner R, Huber R (November 1993). "Refined crystal structure of phycoerythrin from Porphyridium cruentum at 0.23-nm resolution and localization of the gamma subunit". European Journal of Biochemistry. 218 (1): 103â€“6. doi:10.1111/j.1432-1033.1993.tb18356.x. PMID 8243457.
- van der Weij-De Wit CD, Doust AB, van Stokkum IH, Dekker JP, Wilk KE, Curmi PM, Scholes GD, van Grondelle R (December 2006). "How energy funnels from the phycoerythrin antenna complex to photosystem I and photosystem II in cryptophyte Rhodomonas CS24 cells" (PDF). The Journal of Physical Chemistry B. 110 (49): 25066â€“73. doi:10.1021/jp061546w. PMID 17149931. Archived from the original (PDF) on 30 October 2013.
- Six C, Thomas JC, Garczarek L, Ostrowski M, Dufresne A, Blot N, Scanlan DJ & Partensky F (2007). "Diversity and evolution of phycobilisomes in marine Synechococcus spp.: a comparative genomics study". Genome Biology. 8 (12): R259. doi:10.1186/gb-2007-8-12-r259. PMC 2246261. PMID 18062815.
- Glazer AN (1985). "Light harvesting by phycobilisomes". Annual Review of Biophysics and Biophysical Chemistry. 14: 47â€“77. doi:10.1146/annurev.bb.14.060185.000403. PMID 3924069.
- Camara-Artigas, A. (2011-12-16). "Crystal Structure of the B-phycoerythrin from the red algae Porphyridium cruentum at pH8". RCSB Protein Data Bank (PDB). doi:10.2210/pdb3v57/pdb. PDB ID: 3V57. Retrieved 12 October 2012. Cite journal requires
- Camara-Artigas A, Bacarizo J, Andujar-Sanchez M, Ortiz-Salmeron E, Mesa-Valle C, Cuadri C, Martin-Garcia JM, Martinez-Rodriguez S, Mazzuca-Sobczuk T, IbaÃ±ez MJ, Allen JP (October 2012). "pH-dependent structural conformations of B-phycoerythrin from Porphyridium cruentum". The FEBS Journal. 279 (19): 3680â€“3691. doi:10.1111/j.1742-4658.2012.08730.x. PMID 22863205. PDB ID: 3V57.
- Image created with RasTop (Molecular Visualization Software).
- "Protein Data Bank". RCSB Protein Data Bank (PDB). Archived from the original on 28 August 2008. Retrieved 12 October 2012.
- Doust, A.B.; Marai, C.N.J.; Harrop, S.J.; Wilk, K.E.; et al. (2004-09-16). "High resolution crystal structure of phycoerythrin 545 from the marine cryptophyte rhodomonas CS24". RCSB Protein Data Bank (PDB). doi:10.2210/pdb1xg0/pdb. PDB ID: 1XG0. Retrieved 11 October 2012. Cite journal requires
- Doust AB, Marai CN, Harrop SJ, Wilk KE, Curmi PM, Scholes GD (November 2004). "Developing a structure-function model for the cryptophyte phycoerythrin 545 using ultrahigh resolution crystallography and ultrafast laser spectroscopy". Journal of Molecular Biology. 344 (1): 135â€“53. doi:10.1016/j.jmb.2004.09.044. PMID 15504407. PDB ID: 1XG0.
- Contreras-Martel, C.; Legrand, P.; Piras, C.; Vernede, X.; et al. (2000-05-09). "Crystal structure of R-phycoerythrin at 2.2 angstroms". RCSB Protein Data Bank (PDB). doi:10.2210/pdb1eyx/pdb. PDB ID: 1EYX. Retrieved 11 October 2012. Cite journal requires
- Contreras-Martel C, Martinez-Oyanedel J, Bunster M, Legrand P, Piras C, Vernede X, Fontecilla-Camps JC (January 2001). "Crystallization and 2.2 A resolution structure of R-phycoerythrin from Gracilaria chilensis: a case of perfect hemihedral twinning". Acta Crystallographica D. 57 (Pt 1): 52â€“60. doi:10.1107/S0907444900015274. PMID 11134927. PDB ID: 1EYX.
- Apt KE, Hoffman NE, Grossman AR (August 1993). "The gamma subunit of R-phycoerythrin and its possible mode of transport into the plastid of red algae". The Journal of Biological Chemistry. 268 (22): 16208â€“15. PMID 8344905.
- Ritter, S.; Hiller, R.G.; Wrench, P.M.; Welte, W.; et al. (1999-01-29). "Crystal structure of a phycourobilin-containing phycoerythrin". doi:10.2210/pdb1b8d/pdb. PDB ID: 1B8D. Retrieved 14 October 2012. Cite journal requires
- Ritter S, Hiller RG, Wrench PM, Welte W, Diederichs K (June 1999). "Crystal structure of a phycourobilin-containing phycoerythrin at 1.90-A resolution" (PDF). Journal of Structural Biology. 126 (2): 86â€“97. doi:10.1006/jsbi.1999.4106. PMID 10388620. PDB ID: 1B8D.
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.
Phycoerythrin, alpha/beta chain Provide feedback
This family represents the non-globular alpha and beta chain components of phycoerythrin. The structure is a long beta-hairpin and a single alpha-helix.
Wilk KE, Harrop SJ, Jankova L, Edler D, Keenan G, Sharples F, Hiller RG, Curmi PM; , Proc Natl Acad Sci U S A 1999;96:8901-8906.: Evolution of a light-harvesting protein by addition of new subunits and rearrangement of conserved elements: crystal structure of a cryptophyte phycoerythrin at 1.63-A resolution. PUBMED:10430868 EPMC:10430868
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR004228
Cryptophytes are unicellular photosynthetic algae that use a lumenally located light-harvesting system, which is distinct from the phycobilisome structure found in cyanobacteria and red algae. One of the key components of this system is water-soluble phycoerythrin (PE) 545 whose expression is enhanced by low light levels [ PUBMED:10430868 ]. Phycoerythrin (PE) 545 is a heterodimeric of alpha(1)alpha(2)betabeta subunits. Each alpha subunit carries a covalently linked 15,16-dihydrobiliverdin chromophore that probably acts as the final energy acceptor. The architecture of the heterodimer suggests that PE 545 may dock to an acceptor protein via a deep cleft and that energy may be transferred via this intermediary protein to the reaction centre [ PUBMED:10430868 ].
The structure of this domain found in the alpha chain is a long beta-hairpin and a single alpha-helix.
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Cellular component||phycobilisome (GO:0030089)|
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
- a link to the page in the Pfam site showing information about the sequence that the graphic describes
- the UniProt description of the protein sequence
- the number of residues in the sequence
- the Pfam graphic itself.
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.
Finally, because some families can be found in a very large number of architectures, we load only the first fifty architectures by default. If you want to see more architectures, click the button at the bottom of the page to load the next set.
Loading domain graphics...
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...
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:
- the curated alignment from which the HMM for the family is built
- the alignment generated by searching the sequence database using the HMM
- Representative Proteomes (RPs) at 15%, 35%, 55% and 75% co-membership thresholds
- alignment generated by searching the UniProtKB sequence database using the family HMM
You can see the alignments as HTML or in three different sequence viewers:
- a Java applet developed at the University of Dundee. You will need Java installed before running jalview
- an HTML page showing the whole alignment.Please note: full Pfam alignments can be very large. These HTML views are extremely large and often cause problems for browsers. Please use either jalview or the Pfam viewer if you have trouble viewing the HTML version
- an HTML-based representation of the alignment, coloured according to the posterior-probability (PP) values from the HMM. As for the standard HTML view, heatmap alignments can also be very large and slow to render.
You can download (or view in your browser) a text representation of a Pfam alignment in various formats:
You can also change the order in which sequences are listed in the alignment, change how insertions are represented, alter the characters that are used to represent gaps in sequences and, finally, choose whether to download the alignment or to view it in your browser directly.
You may find that large alignments cause problems for the viewers and the reformatting tool, so we also provide all alignments in Stockholm format. You can download either the plain text alignment, or a gzipped version of it.
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.
You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.
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...
If you find these logos useful in your own work, please consider citing the following article:
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.
|Seed source:||Structural domain|
|Number in seed:||5|
|Number in full:||21|
|Average length of the domain:||56.50 aa|
|Average identity of full alignment:||49 %|
|Average coverage of the sequence by the domain:||42.57 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 57096847 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||16|
|Download:||download the raw HMM for this family|
Weight segments by...
Change the size of the sunburst
selected sequences to HMM
a FASTA-format file
- 0 sequences
- 0 species
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
- 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
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.
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 Phycoerythr_ab domain has been found. There are 16 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.
Loading structure mapping...