Summary: Flavinator of succinate dehydrogenase
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Succinate dehydrogenase complex subunit C Edit Wikipedia article
|Succinate dehydrogenase complex, subunit C, integral membrane protein, 15kDa|
PDB rendering based on 1zp0.
|Symbols||; CYB560; CYBL; PGL3; QPS1; SDH3|
Succinate dehydrogenase complex subunit C, also known as succinate dehydrogenase cytochrome b560 subunit, mitochondrial, is a protein that in humans is encoded by the SDHC gene. This gene encodes one of four nuclear-encoded subunits that comprise succinate dehydrogenase, also known as mitochondrial complex II, a key enzyme complex of the tricarboxylic acid cycle and aerobic respiratory chains of mitochondria. The encoded protein is one of two integral membrane proteins that anchor other subunits of the complex, which form the catalytic core, to the inner mitochondrial membrane. There are several related pseudogenes for this gene on different chromosomes. Mutations in this gene have been associated with paragangliomas. Alternatively spliced transcript variants have been described.
The gene that codes for the SDHC protein is nuclear, even though the protein is located in the inner membrane of the mitochondria. The location of the gene in humans is on the first chromosome at q21. The gene is partitioned in 6 exons. The SDHC gene produces an 18.6 kDa protein composed of 169 amino acids.
The SDHC protein is one of the two transmembrane subunits of the four-subunit succinate dehydrogenase (Complex II) protein complex that resides in the inner mitochondrial membrane. The other transmembrane subunit is SDHD. The SDHC/SDHD dimer is connected to the SDHB electron transport subunit which, in turn, is connected to the SDHA subunit.
The SDHC protein is one of four nuclear-encoded subunits that comprise succinate dehydrogenase, also known as Complex II of the electron transport chain, a key enzyme complex of the citric acid cycle and aerobic respiratory chains of mitochondria. The encoded protein is one of two integral membrane proteins that anchor other subunits of the complex, which form the catalytic core, to the inner mitochondrial membrane.
SDHC forms part of the transmembrane protein dimer with SDHD that anchors Complex II to the inner mitochondrial membrane. The SDHC/SDHD dimer provides binding sites for ubiquinone and water during electron transport at Complex II. Initially, SDHA oxidizes succinate via deprotonation at the FAD binding site, forming FADH2 and leaving fumarate, loosely bound to the active site, free to exit the protein. The electrons derived from succinate tunnel along the [Fe-S] relay in the SDHB subunit until they reach the [3Fe-4S] iron sulfur cluster. The electrons are then transferred to an awaiting ubiquinone molecule at the Q pool active site in the SDHC/SDHD dimer. The O1 carbonyl oxygen of ubiquinone is oriented at the active site (image 4) by hydrogen bond interactions with Tyr83 of SDHD. The presence of electrons in the [3Fe-4S] iron sulphur cluster induces the movement of ubiquinone into a second orientation. This facilitates a second hydrogen bond interaction between the O4 carbonyl group of ubiquinone and Ser27 of SDHC. Following the first single electron reduction step, a semiquinone radical species is formed. The second electron arrives from the [3Fe-4S] cluster to provide full reduction of the ubiquinone to ubiquinol.
Mutations in this gene have been associated with paragangliomas. More than 30 mutations in the SDHC gene have been found to increase the risk of hereditary paraganglioma-pheochromocytoma type 3. People with this condition have paragangliomas, pheochromocytomas, or both. An inherited SDHC gene mutation predisposes an individual to the condition, and a somatic mutation that deletes the normal copy of the SDHC gene is needed to cause hereditary paraganglioma-pheochromocytoma type 3. Most of the inherited SDHC gene mutations change single amino acids in the SDHC protein sequence or result in a shortened protein. As a result, there is little or no SDH enzyme activity. Because the mutated SDH enzyme cannot convert succinate to fumarate, succinate accumulates in the cell. The excess succinate abnormally stabilizes hypoxia-inducible factors (HIF), which also builds up in cells. Excess HIF stimulates cells to divide and triggers the production of blood vessels when they are not needed. Rapid and uncontrolled cell division, along with the formation of new blood vessels, can lead to the development of tumors in people with hereditary paraganglioma-pheochromocytoma.
Interactive pathway map
Click on genes, proteins and metabolites below to link to respective articles. [Â§ 1]
- The interactive pathway map can be edited at WikiPathways: "TCACycle_WP78".
- Hirawake H, Taniwaki M, Tamura A, Kojima S, Kita K (1997). "Cytochrome b in human complex II (succinate-ubiquinone oxidoreductase): cDNA cloning of the components in liver mitochondria and chromosome assignment of the genes for the large (SDHC) and small (SDHD) subunits to 1q21 and 11q23". Cytogenet. Cell Genet. 79 (1-2): 132â€“8. doi:10.1159/000134700. PMID 9533030.
- "Entrez Gene: succinate dehydrogenase complex".
- Zong NC, Li H, Li H, Lam MP, Jimenez RC, Kim CS et al. (Oct 2013). "Integration of cardiac proteome biology and medicine by a specialized knowledgebase". Circulation Research 113 (9): 1043â€“53. doi:10.1161/CIRCRESAHA.113.301151. PMC 4076475. PMID 23965338.
- "SDHC - Succinate dehydrogenase cytochrome b560 subunit, mitochondrial". Cardiac Organellar Protein Atlas Knowledgebase (COPaKB).
- Sun, F; Huo, X; Zhai, Y; Wang, A; Xu, J; Su, D; Bartlam, M; Rao, Z (1 July 2005). "Crystal structure of mitochondrial respiratory membrane protein complex II.". Cell 121 (7): 1043â€“57. doi:10.1016/j.cell.2005.05.025. PMID 15989954.
- Horsefield, R; Yankovskaya, V; Sexton, G; Whittingham, W; Shiomi, K; Omura, S; Byrne, B; Cecchini, G; Iwata, S (17 March 2006). "Structural and computational analysis of the quinone-binding site of complex II (succinate-ubiquinone oxidoreductase): a mechanism of electron transfer and proton conduction during ubiquinone reduction.". The Journal of biological chemistry 281 (11): 7309â€“16. doi:10.1074/jbc.m508173200. PMID 16407191.
- Niemann S, MÃ¼ller U, Engelhardt D, Lohse P (July 2003). "Autosomal dominant malignant and catecholamine-producing paraganglioma caused by a splice donor site mutation in SDHC". Hum. Genet. 113 (1): 92â€“4. doi:10.1007/s00439-003-0938-0. PMID 12658451.
- "SDHC". Genetics Home Reference. U.S. National Library of Medicine. Retrieved 26 March 2015.
- Bayley JP, Weiss MM, Grimbergen A et al. (2009). "Molecular characterization of novel germline deletions affecting SDHD and SDHC in pheochromocytoma and paraganglioma patients.". Endocr. Relat. Cancer 16 (3): 929â€“37. doi:10.1677/ERC-09-0084. PMID 19546167.
- Pasini B, McWhinney SR, Bei T et al. (2008). "Clinical and molecular genetics of patients with the Carney-Stratakis syndrome and germline mutations of the genes coding for the succinate dehydrogenase subunits SDHB, SDHC, and SDHD.". Eur. J. Hum. Genet. 16 (1): 79â€“88. doi:10.1038/sj.ejhg.5201904. PMID 17667967.
- Gaal J, Burnichon N, Korpershoek E et al. (2010). "Isocitrate dehydrogenase mutations are rare in pheochromocytomas and paragangliomas.". J. Clin. Endocrinol. Metab. 95 (3): 1274â€“8. doi:10.1210/jc.2009-2170. PMID 19915015.
- Milosevic D, Lundquist P, Cradic K et al. (2010). "Development and validation of a comprehensive mutation and deletion detection assay for SDHB, SDHC, and SDHD.". Clin. Biochem. 43 (7-8): 700â€“4. doi:10.1016/j.clinbiochem.2010.01.016. PMC 3419008. PMID 20153743.
- Bonache S, MartÃnez J, FernÃ¡ndez M et al. (2007). "Single nucleotide polymorphisms in succinate dehydrogenase subunits and citrate synthase genes: association results for impaired spermatogenesis.". Int. J. Androl. 30 (3): 144â€“52. doi:10.1111/j.1365-2605.2006.00730.x. PMID 17298551.
- CascÃ¡n A, LÃ¡pez-JimÃ©nez E, Landa I et al. (2009). "Rationalization of genetic testing in patients with apparently sporadic pheochromocytoma/paraganglioma.". Horm. Metab. Res. 41 (9): 672â€“5. doi:10.1055/s-0029-1202814. PMID 19343621.
- Goto Y, Ando T, Naito M et al. (2006). "No association of an SDHC gene polymorphism with gastric cancer.". Asian Pac. J. Cancer Prev. 7 (4): 525â€“8. PMID 17250422.
- CascÃ¡n A, Pita G, Burnichon N et al. (2009). "Genetics of pheochromocytoma and paraganglioma in Spanish patients.". J. Clin. Endocrinol. Metab. 94 (5): 1701â€“5. doi:10.1210/jc.2008-2756. PMID 19258401.
- Boedeker CC, Neumann HP, Maier W et al. (2007). "Malignant head and neck paragangliomas in SDHB mutation carriers.". Otolaryngol Head Neck Surg 137 (1): 126â€“9. doi:10.1016/j.otohns.2007.01.015. PMID 17599579.
- Gill AJ, Benn DE, Chou A et al. (2010). "Immunohistochemistry for SDHB triages genetic testing of SDHB, SDHC, and SDHD in paraganglioma-pheochromocytoma syndromes.". Hum. Pathol. 41 (6): 805â€“14. doi:10.1016/j.humpath.2009.12.005. PMID 20236688.
- Ricketts C, Woodward ER, Killick P et al. (2008). "Germline SDHB mutations and familial renal cell carcinoma.". J. Natl. Cancer Inst. 100 (17): 1260â€“2. doi:10.1093/jnci/djn254. PMID 18728283.
- McWhinney SR, Pasini B, Stratakis CA, (2007). "Familial gastrointestinal stromal tumors and germ-line mutations.". N. Engl. J. Med. 357 (10): 1054â€“6. doi:10.1056/NEJMc071191. PMID 17804857.
- Eng C, Kiuru M, Fernandez MJ, Aaltonen LA (2003). "A role for mitochondrial enzymes in inherited neoplasia and beyond.". Nat. Rev. Cancer 3 (3): 193â€“202. doi:10.1038/nrc1013. PMID 12612654.
- Hermsen MA, Sevilla MA, Llorente JL et al. (2010). "Relevance of germline mutation screening in both familial and sporadic head and neck paraganglioma for early diagnosis and clinical management.". Cell. Oncol. 32 (4): 275â€“83. doi:10.3233/CLO-2009-0498. PMID 20208144.
- BriÃÂ¨re JJ, Favier J, El Ghouzzi V et al. (2005). "Succinate dehydrogenase deficiency in human.". Cell. Mol. Life Sci. 62 (19-20): 2317â€“24. doi:10.1007/s00018-005-5237-6. PMID 16143825.
- Mannelli M, Castellano M, Schiavi F et al. (2009). "Clinically guided genetic screening in a large cohort of italian patients with pheochromocytomas and/or functional or nonfunctional paragangliomas.". J. Clin. Endocrinol. Metab. 94 (5): 1541â€“7. doi:10.1210/jc.2008-2419. PMID 19223516.
- Richalet JP, Gimenez-Roqueplo AP, Peyrard S et al. (2009). "A role for succinate dehydrogenase genes in low chemoresponsiveness to hypoxia?". Clin. Auton. Res. 19 (6): 335â€“42. doi:10.1007/s10286-009-0028-z. PMID 19768395.
- Pigny P, Cardot-Bauters C, Do Cao C et al. (2009). "Should genetic testing be performed in each patient with sporadic pheochromocytoma at presentation?". Eur. J. Endocrinol. 160 (2): 227â€“31. doi:10.1530/EJE-08-0574. PMID 19029228.
- Korpershoek E, Van Nederveen FH, Dannenberg H et al. (2006). "Genetic analyses of apparently sporadic pheochromocytomas: the Rotterdam experience.". Ann. N. Y. Acad. Sci. 1073: 138â€“48. doi:10.1196/annals.1353.014. PMID 17102080.
- Wang L, McDonnell SK, Hebbring SJ et al. (2008). "Polymorphisms in mitochondrial genes and prostate cancer risk.". Cancer Epidemiol. Biomarkers Prev. 17 (12): 3558â€“66. doi:10.1158/1055-9965.EPI-08-0434. PMC 2750891. PMID 19064571.
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.
Flavinator of succinate dehydrogenase Provide feedback
This family includes the highly conserved mitochondrial and bacterial proteins Sdh5/SDHAF2/SdhE. Both yeast and human Sdh5/SDHAF2 interact with the catalytic subunit of the succinate dehydrogenase (SDH) complex, a component of both the electron transport chain and the tricarboxylic acid cycle. Sdh5 is required for SDH-dependent respiration and for Sdh1 flavination (incorporation of the flavin adenine dinucleotide cofactor). Mutational inactivation of Sdh5 confers tumor susceptibility in humans . Bacterial homologues of Sdh5, termed SdhE, are functionally conserved being required for the flavinylation of SdhA and succinate dehydrogenase activity. Like Sdh5, SdhE interacts with SdhA. Furthermore, SdhE was characterised as a FAD co-factor chaperone that directly binds FAD to facilitate the flavinylation of SdhA. Phylogenetic analysis demonstrates that SdhE/Sdh5 proteins evolved only once in an ancestral alpha-proteobacteria prior to the evolution of the mitochondria and now remain in subsequent descendants including eukaryotic mitochondria and the alpha, beta and gamma proteobacteria . This family was previously annotated in Pfam as being a divergent TPR repeat but structural evidence has indicated this is not true. The E. coli protein, YgfY also acts as the antitoxin to the membrane-bound toxin family Cpta, PF13166 whose E. coli member YgfX, expressed from the same operon as YgfY .
Hao HX, Khalimonchuk O, Schraders M, Dephoure N, Bayley JP, Kunst H, Devilee P, Cremers CW, Schiffman JD, Bentz BG, Gygi SP, Winge DR, Kremer H, Rutter J;, Science. 2009;325:1139-1142.: SDH5, a gene required for flavination of succinate dehydrogenase, is mutated in paraganglioma. PUBMED:19628817 EPMC:19628817
McNeil MB, Clulow JS, Wilf NM, Salmond GP, Fineran PC;, J. Biol. Chem. 2012;0:0-0.: SdhE is a conserved protein required for the flavinylation of succinate dehydrogenase in bacteria. PUBMED:22474332 EPMC:22474332
Masuda H, Tan Q, Awano N, Yamaguchi Y, Inouye M;, FEMS Microbiol Lett. 2012;328:174-181.: A novel membrane-bound toxin for cell division, CptA (YgfX), inhibits polymerization of cytoskeleton proteins, FtsZ and MreB, in Escherichia coli. PUBMED:22239607 EPMC:22239607
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR005631
This family includes the highly conserved mitochondrial and bacterial proteins Sdh5/SDHAF2/SdhE.
Both yeast and human Sdh5/SDHAF2 interact with the catalytic subunit of the succinate dehydrogenase (SDH) complex, a component of both the electron transport chain and the tricarboxylic acid cycle. Sdh5 is required for SDH-dependent respiration and for Sdh1 flavination (incorporation of the flavin adenine dinucleotide cofactor). Mutational inactivation of Sdh5 confers tumor susceptibility in humans [PUBMED:19628817].
Bacterial homologues of Sdh5, termed SdhE, are functionally conserved being required for the flavinylation of SdhA and succinate dehydrogenase activity. Like Sdh5, SdhE interacts with SdhA. Furthermore, SdhE was characterised as a FAD co-factor chaperone that directly binds FAD to facilitate the flavinylation of SdhA. Phylogenetic analysis demonstrates that SdhE/Sdh5 proteins evolved only once in an ancestral alpha-proteobacteria prior to the evolution of the mitochondria and now remain in subsequent descendants including eukaryotic mitochondria and the alpha, beta and gamma proteobacteria [PUBMED:22474332].
This family was previously annotated in Pfam as being a divergent TPR repeat but structural evidence has indicated this is not true.
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:
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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
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You can see the alignments as HTML or in three different sequence viewers:
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You can download (or view in your browser) a text representation of a Pfam alignment in various formats:
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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.
You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.
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 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...
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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.
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.
|Previous IDs:||DUF339; TPR_div1;|
|Author:||Bateman A, Yeats C, McNeil M, Eberhardt R|
|Number in seed:||306|
|Number in full:||7206|
|Average length of the domain:||71.00 aa|
|Average identity of full alignment:||44 %|
|Average coverage of the sequence by the domain:||73.14 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 80369284 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||12|
|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:
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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 is 1 interaction 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 Sdh5 domain has been found. There are 6 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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