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This is the Wikipedia entry entitled "Phospholamban". More...
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Phospholamban Edit Wikipedia article
PDB rendering based on 1fjk.
|RNA expression pattern|
Phospholamban, also known as PLN or PLB, is a protein that in humans is encoded by the PLN gene. Phospholamban is a 52-amino acid integral membrane protein that regulates the Ca2+ pump in cardiac muscle and skeletal muscle cells.
This protein is found as a pentamer and is a major substrate for the cAMP-dependent protein kinase (PKA) in cardiac muscle. The protein is an inhibitor of cardiac muscle sarcoplasmic reticulum Ca++-ATPase (SERCA) in the unphosphorylated state, but inhibition is relieved upon phosphorylation of the protein. The subsequent activation of the Ca++ pump leads to shorter intervals between contractions, thereby contributing to the lusitropic response elicited in heart by beta-agonists. The protein is a key regulator of . Mutations in this gene are a cause of inherited human dilated cardiomyopathy with refractory congestive heart failure.
When phospholamban is phosphorylated by its ability to inhibit the sarcoplasmic reticulum calcium pump (SERCA) is lost. Thus, activators of PKA, such as the beta-adrenergic agonist epinephrine (released by sympathetic stimulation), may enhance the rate of cardiac myocyte relaxation. In addition, since SERCA is more active, the next action potential will cause an increased release of calcium, resulting in increased contraction (positive inotropic effect). When phospholamban is not phosphorylated, such as when PKA is inactive, it can interact with and inhibit SERCA. The overall effect of phospholamban is to decrease and the rate of , thereby decreasing stroke volume and heart rate, respectively.
Gene knockout of phospholamban results in animals with hyperdynamic hearts, with little apparent negative consequence.
Mutations in this gene are a cause of inherited human dilated with refractory .
Phospholamban was discovered by Arnold Katz and coworkers in 1974.
- Fujii J, Zarain-Herzberg A, Willard HF, Tada M, MacLennan DH (June 1991). "Structure of the rabbit phospholamban gene, cloning of the human cDNA, and assignment of the gene to human chromosome 6". J. Biol. Chem. 266 (18): 11669–75. PMID 1828805.
- Rodriguez P, Kranias EG (December 2005). "Phospholamban: a key determinant of cardiac function and dysfunction". Arch Mal Coeur Vaiss 98 (12): 1239–43. PMID 16435604.
- "Entrez Gene: PLN phospholamban".
- Medical Physiology. Philadelphia: Saunders. 2004. ISBN 0-8089-2333-1.
- Brittsan AG, Kranias EG (December 2000). "Phospholamban and cardiac contractile function". J. Mol. Cell. Cardiol. 32 (12): 2131–9. doi:10.1006/jmcc.2000.1270. PMID 11112989.
- Luo W, Grupp IL, Harrer J, Ponniah S, Grupp G, Duffy JJ, Doetschman T, Kranias EG (September 1994). "Targeted ablation of the phospholamban gene is associated with markedly enhanced myocardial contractility and loss of beta-agonist stimulation". Circ. Res. 75 (3): 401–9. PMID 8062415.
- Schmitt JP, Kamisago M, Asahi M, Li GH, Ahmad F, Mende U, Kranias EG, MacLennan DH, Seidman JG, Seidman CE (February 2003). "Dilated cardiomyopathy and heart failure caused by a mutation in phospholamban". Science 299 (5611): 1410–3. doi:10.1126/science.1081578. PMID 12610310.
- Tada M, Kirchberger MA, Repke DI, Katz AM (October 1974). "The stimulation of calcium transport in cardiac sarcoplasmic reticulum by adenosine 3':5'-monophosphate-dependent protein kinase". J Biol Chem 10 (249(19)): 6174–80. PMID 4371608.
- Asahi, Michio; Sugita Yuji, Kurzydlowski Kazimierz, De Leon Stella, Tada Michihiko, Toyoshima Chikashi, MacLennan David H (Apr 2003). "Sarcolipin regulates sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) by binding to transmembrane helices alone or in association with phospholamban". Proc. Natl. Acad. Sci. U.S.A. (United States) 100 (9): 5040–5. doi:10.1073/pnas.0330962100. ISSN 0027-8424. PMC 154294. PMID 12692302.
- Asahi, Michio; Kurzydlowski Kazimierz, Tada Michihiko, MacLennan David H (Jul 2002). "Sarcolipin inhibits polymerization of phospholamban to induce superinhibition of sarco(endo)plasmic reticulum Ca2+-ATPases (SERCAs)". J. Biol. Chem. (United States) 277 (30): 26725–8. doi:10.1074/jbc.C200269200. ISSN 0021-9258. PMID 12032137.
- Asahi, M; Kimura Y, Kurzydlowski K, Tada M, MacLennan D H (Nov 1999). "Transmembrane helix M6 in sarco(endo)plasmic reticulum Ca(2+)-ATPase forms a functional interaction site with phospholamban. Evidence for physical interactions at other sites". J. Biol. Chem. (UNITED STATES) 274 (46): 32855–62. doi:10.1074/jbc.274.46.32855. ISSN 0021-9258. PMID 10551848.
- Asahi, M; Green N M, Kurzydlowski K, Tada M, MacLennan D H (Aug 2001). "Phospholamban domain IB forms an interaction site with the loop between transmembrane helices M6 and M7 of sarco(endo)plasmic reticulum Ca2+ ATPases". Proc. Natl. Acad. Sci. U.S.A. (United States) 98 (18): 10061–6. doi:10.1073/pnas.181348298. ISSN 0027-8424. PMC 56915. PMID 11526231.
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Phospholamban Provide feedback
The regulation of calcium levels across the membrane of the sarcoplasmic reticulum involves the interplay of many membrane proteins. Phospholamban is a 52 residue integral membrane protein that is involved in reversibly inhibiting the Ca(2+) pump and regulating the flow of Ca ions across the sarcoplasmic reticulum membrane during muscle contraction and relaxation . Phospholamban is thought to form a pentamer in the membrane .
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR005984
Phospholamban (PLB) is a small protein (52 amino acids) that regulates the affinity of the cardiac sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) for calcium. PLB is present in cardiac myocytes, in slow-twitch and smooth muscle and is expressed also in aorta endothelial cells in which it could play a role in tissue relaxation. The phosphorylation/dephosphorylation of phospholamban removes and restores, respectively, its inhibitory activity on SERCA2a. It has in fact been shown that phospholamban, in its non-phosphorylated form, binds to SERCA2a and inhibits this pump by lowering its affinity for Ca2+, whereas the phosphorylated form does not exert the inhibition. PLB is phosphorylated at two sites, namely at Ser-16 for a cAMP-dependent phosphokinase and at Thr-17 for a Ca2+/calmodulin-dependent phosphokinase, phosphorylation at Ser-16 being a prerequisite for the phosphorylation at Thr-17.
The structure of a 36-amino-acid-long N-terminal fragment of human phospholamban phosphorylated at Ser-16 and Thr-17 and Cys36Ser mutated was determined from nuclear magnetic resonance data. The peptide assumes a conformation characterised by two alpha-helices connected by an irregular strand, which comprises the amino acids from Arg-13 to Pro-21. The proline is in a trans conformation. The two phosphate groups on Ser-16 and Thr-17 are shown to interact preferably with the side chains of Arg-14 and Arg-13, respectively [PUBMED:12080135].
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Cellular component||membrane (GO:0016020)|
|Molecular function||ATPase inhibitor activity (GO:0042030)|
|calcium channel regulator activity (GO:0005246)|
|Biological process||calcium ion transport (GO:0006816)|
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
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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
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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:
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.
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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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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:||TIGRFAMs (release 2.0);|
|Author:||TIGRFAMs, Finn RD|
|Number in seed:||2|
|Number in full:||32|
|Average length of the domain:||52.00 aa|
|Average identity of full alignment:||90 %|
|Average coverage of the sequence by the domain:||96.41 %|
|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:||9|
|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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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 Phospholamban domain has been found. There are 15 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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