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This is the Wikipedia entry entitled "Motilin". More...
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Motilin Edit Wikipedia article
||It has been suggested that Motilin family be merged into this article or section. (Discuss) Proposed since May 2011.|
NMR solution structure of motilin in phospholipid bicellar solution.
|Locus||Chr. 6 p21.3-p21.2|
Motilin is secreted by endocrine M cells (these are not the same M cells that are in Peyer's patches) that are numerous in crypts of the small intestine, especially in the duodenum and jejunum. Based on amino acid sequence, motilin is unrelated to other hormones. Because of its ability to stimulate gastric activity, it was named "Motilin". Apart from in humans, motilin receptors are found in the gastrointestinal tracts of pigs, rats, cows, and cats, and in the central nervous system of rabbits.
Motilin was discovered by J.C. Brown when he introduced alkaline solution into duodena of dogs, which caused strong gastric contractions. Brown et al. predicted that alkali could either release stimulus to activate motor activity or prevent the secretion of inhibitory hormone. They isolated a polypeptide as a byproduct from purification of secretin on carboxymethyl cellulose. They named this polypeptide âMotilin.â
Motilin has 22 amino acids and molecular weight of 2698. In extract from human gut and plasma, there are two basic forms of motilin. The first molecular form is the polypeptide of 22 amino acids. The second form, on the other hand, is larger and contains the same 22 amino acids as the first form but includes an additional carboxyl-terminus end.
The structure and dynamics of the gastrointestinal peptide hormone motilin have been studied in the presence of isotropic q = 0.5 phospholipid bicelles. The NMR solution structure of the peptide in acidic bicelle solution was determined from 203 NOE-derived distance constraints and six backbone torsion angle constraints. Dynamic properties for the 13CÎ±â1H vector in Leu-10 were determined for motilin specifically labeled with 13C at this position by analysis of multiple-field relaxation data. The structure reveals an ordered alpha-helical conformation between Glu-9 and Lys-20. The N-terminus is also well structured with a turn resembling that of a classical beta-turn. The 13C dynamics clearly show that motilin tumbles slowly in solution, with a correlation time characteristic of a large object.
Control of motilin secretion is largely unknown, although some studies suggest that an alkaline pH in the duodenum stimulates its release. It is interesting to note, however, that at low pH it inhibits gastric motor activity, whereas at high pH it has a stimulatory effect. Some studies in dogs have shown that motilin is released during fasting or interdigestive period, and intake of food during this period can prevent the secretion of motilin. Intravenous injection of glucose, which increases the release of insulin, is also found to inhibit cyclic elevation of plasma motilin. Other studies on dogs have also suggested that motilin acted as endogenous ligand in positive feedback mechanism to stimulate the release of more motilin.
The main function of motilin is to increase the migrating myoelectric complex component of gastrointestinal motility and stimulate the production of pepsin. Motilin is also called "Housekeeper of the gut" because it improves peristalsis in the small intestine and clears out the gut to prepare for the next meal. A high level of motilin secreted between meals into the blood stimulates the contraction of the fundus and antrum and accelerates gastric emptying. It then contracts the gallbladder and increases the squeeze pressure of the lower esophageal sphincter. Other functions of motilin include increasing the release of pancreatic polypeptide and somatostatin
 Motilin agonists
Erythromycin and related antibiotics act as non-peptide motilin agonists, and are sometimes used for their ability to stimulate gastrointestinal motility. Administration of a low dose of erythromycin will induce peristalsis, which provides additional support for the conclusion that motilin secretion triggers this pattern of gastrointestinal motility, rather than results from it. However, some of erythromycinâs properties, including antibiotic activity, are not appropriate for a drug designed for chronic use over a patient's lifetime.
New motilin agonists are erythromycin-based; however, it may be that this class of drugs becomes redundant. Growth hormone secretagogue receptors share 52% of their DNA with motilin receptors, and agonists of these receptors, termed ghrelins, can bring about similar effects to motilin agonists.
 Related peptides
This domain is also found in ghrelin, a growth hormone secretagogue synthesised by endocrine cells in the stomach. Ghrelin stimulates growth hormone secretagogue receptors in the pituitary. These receptors are distinct from the growth hormone-releasing hormone receptors, and, thus, provide a means of controlling pituitary growth hormone release by the gastrointestinal system. Erythromycin has an advantage over metoclopramide in gastric emptying due to lack of central nervous system side-effects. It is not approved by FDA to use for gastric emptying. For short duration for patients with diabetes and for those that must clear the stomach for any procedure, it may be used based on the physician's discretion with full understanding that it is not approved by FDA for this use.
- PDB 1lbj; Andersson A, MÃ¤ler L (October 2002). "NMR solution structure and dynamics of motilin in isotropic phospholipid bicellar solution". J. Biomol. NMR 24 (2): 103â12. doi:10.1023/A:1020902915969. PMID 12495026.
- Daikh DI, Douglass JO, Adelman JP (October 1989). "Structure and expression of the human motilin gene". DNA 8 (8): 615â21. doi:10.1089/dna.1989.8.615. PMID 2574660.
- Poitras P, Peeters TL (February 2008). "Motilin". Curr Opin Endocrinol Diabetes Obes 15 (1): 54â7. doi:10.1097/MED.0b013e3282f370af. PMID 18185063.
- Brown JC, Cook MA, Dryburgh JR (May 1973). "Motilin, a gastric motor activity stimulating polypeptide: the complete amino acid sequence". Canadian journal of biochemistry 51 (5): 533â7. doi:10.1139/o73-066. PMID 4706833.
- DeGroot, Leslie Jacob (1989). In J.E. McGuigan. Endocrinology. Philadelphia: Saunders. p. 2748. ISBN 0-7216-2888-5.
- Williams, Robert L. (1981). Textbook of endocrinology (6th ed.). Philadelphia: Saunders. pp. 704â705. ISBN 0-7216-9398-9.
- Itoh Z, Takeuchi S, Aizawa I, Mori K, Taminato T, Seino Y, Imura H, Yanaihara N. (October 1978). "Changes in plasma motilin concentration and gastrointestinal contractile activity in conscious dogs". The American journal of digestive diseases 23 (10): 929â35. doi:10.1007/BF01072469. PMID 717352.
- Lemoyne M, Wassef R, TassÃ© D, Trudel L, Poitras P (September 1984). "Motilin and the vagus in dogs". Canadian Journal of Physiology and Pharmacology 62 (9): 1092â6. PMID 6388765.
- Hall KE, Greenberg GR, El-Sharkawy TY, Diamant NE (July 1984). "Relationship between porcine motilin-induced migrating motor complex-like activity, vagal integrity, and endogenous motilin release in dogs". Gastroenterology 87 (1): 76â85. PMID 6724277.
- Frohman, Lawrence A.; Felig, Philip (2001). In P. K. Ghosh and T. M. OâDorisio. Endocrinology & metabolism. New York: McGraw-Hill, Medical Pub. Div. p. 1330. ISBN 0-07-022001-8.
- Kangawa K, Matsuo H, Kojima M, Hosoda H (2001). "Ghrelin: discovery of the natural endogenous ligand for the growth hormone secretagogue receptor". Trends Endocrinol. Metab. 12 (3): 118â122. doi:10.1016/S1043-2760(00)00362-3. PMID 11306336.
- Motilin at the US National Library of Medicine Medical Subject Headings (MeSH)
- Physiology at MCG 6/6ch2/s6ch2_26
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.
Motilin/ghrelin Provide feedback
Motilin is a gastrointestinal regulatory polypeptide produced by motilin cells in the duodenal epithelium. It is released into the general circulation at about 100-min intervals during the inter-digestive state and is the most important factor in controlling the inter-digestive migrating contractions. Motilin also stimulates endogenous release of the endocrine pancreas . This family also includes ghrelin, a growth hormone secretagogue synthesised by endocrine cells in the stomach. Ghrelin stimulates growth hormone secretagogue receptors in the pituitary. These receptors are distinct from the growth hormone-releasing hormone receptors, and thus provide a means of controlling pituitary growth hormone release by the gastrointestinal system .
Kojima M, Hosoda H, Matsuo H, Kangawa K; , Trends Endocrinol Metab 2001;12:118-122.: Ghrelin: discovery of the natural endogenous ligand for the growth hormone secretagogue receptor. PUBMED:11306336 EPMC:11306336
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR006738
Motilin is a gastrointestinal regulatory polypeptide produced by motilin cells in the duodenal epithelium. It is released into the general circulation at about 100-min intervals during the inter-digestive state and is the most important factor in controlling the inter-digestive migrating contractions. Motilin also stimulates endogenous release of the endocrine pancreas [PUBMED:9210180].
This domain is also found in ghrelin, a growth hormone secretagogue synthesised by endocrine cells in the stomach. Ghrelin stimulates growth hormone secretagogue receptors in the pituitary. These receptors are distinct from the growth hormone-releasing hormone receptors, and thus provide a means of controlling pituitary growth hormone release by the gastrointestinal system [PUBMED:11306336].
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Cellular component||extracellular region (GO:0005576)|
|Molecular function||hormone activity (GO:0005179)|
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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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.
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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:||Pfam-B_5485 (release 7.5)|
|Number in seed:||6|
|Number in full:||118|
|Average length of the domain:||27.20 aa|
|Average identity of full alignment:||59 %|
|Average coverage of the sequence by the domain:||26.77 %|
|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:||7|
|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.
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 Motilin_ghrelin domain has been found. There are 1 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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