Mechanosensitive ion channel: Difference between revisions
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{{Infobox protein family |
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| Symbol = MS_channel |
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| Name = MS_channel |
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| image = |
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| width = |
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| caption = the open structure of mscs |
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| Pfam = PF00924 |
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| Pfam_clan = |
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| InterPro = IPR006685 |
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| SMART = |
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| PROSITE = PDOC00959 |
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| MEROPS = |
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| SCOP = 1mxm |
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| TCDB = 1.A.23 |
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| OPM family = 11 |
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| OPM protein = 2vv5 |
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| CAZy = |
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| CDD = |
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}} |
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'''Mechanosensitive channels''' (MS channels) are found in a number of tissues and organisms and are thought to be the sensors for a number of systems including the senses of touch, hearing and balance, as well as participating in cardiovascular regulation and osmotic homeostasis (e.g. thirst). They are present in the membranes of organisms from the three domains of life: bacteria, archaea, and eukarya.<ref name="pmid12626684">{{cite journal | author = Pivetti CD, Yen MR, Miller S, Busch W, Tseng YH, Booth IR, Saier MH | title = Two families of mechanosensitive channel proteins | journal = Microbiol. Mol. Biol. Rev. | volume = 67 | issue = 1 | pages = 66–85, table of contents | year = 2003 | month = March | pmid = 12626684 | pmc = 150521 | doi = 10.1128/MMBR.67.1.66-85.2003 }}</ref> Mechanosensitive channels were first observed in chick skeletal muscles by Falguni Guharay and Frederick Sachs in 1983 and the results were published in 1984.<ref name="pmid6086918">{{cite journal | author = Guharay F, Sachs F | title = Stretch-activated single ion channel currents in tissue-cultured embryonic chick skeletal muscle | journal = J. Physiol. (Lond.) | volume = 352 | issue = | pages = 685–701 | year = 1984 | month = July | pmid = 6086918 | pmc = 1193237 | doi = }}</ref> |
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For a protein to be considered mechanosensitive, it must respond to a mechanical deformation of the membrane. Mechanical deformations can include changes in the tension, thickness, or curvature of the membrane. Mechanosensitive channels respond to membrane tension by altering their conformation between an open state and a closed state.<ref name="pmid7690260">{{cite journal | author = Sukharev SI, Martinac B, Arshavsky VY, Kung C | title = Two types of mechanosensitive channels in the Escherichia coli cell envelope: solubilization and functional reconstitution | journal = Biophys. J. | volume = 65 | issue = 1 | pages = 177–83 | year = 1993 | month = July | pmid = 7690260 | pmc = 1225713 | doi = 10.1016/S0006-3495(93)81044-0 }}</ref><ref name="pmid22000509">{{cite journal | author = Haswell ES, Phillips R, Rees DC | title = Mechanosensitive channels: what can they do and how do they do it? | journal = Structure | volume = 19 | issue = 10 | pages = 1356–69 | year = 2011 | month = October | pmid = 22000509 | pmc = 3203646 | doi = 10.1016/j.str.2011.09.005 }}</ref> One type of mechanically sensitive ion channel activates specialized sensory cells, such as cochlear [[hair cell]]s and some touch [[sensory neuron]]s, in response to forces applied to proteins.<ref name="pmid12429699">{{cite journal | author = Ernstrom GG, Chalfie M | title = Genetics of sensory mechanotransduction | journal = Annu. Rev. Genet. | volume = 36 | issue = | pages = 411–53 | year = 2002 | pmid = 12429699 | doi = 10.1146/annurev.genet.36.061802.101708 }}</ref><ref name="pmid8805263">{{cite journal | author = García-Añoveros J, Corey DP | title = Touch at the molecular level. Mechanosensation | journal = Curr. Biol. | volume = 6 | issue = 5 | pages = 541–3 | year = 1996 | month = May | pmid = 8805263 | doi = 10.1016/S0960-9822(02)00537-7 }}</ref> |
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In eukaryotes, two of the best known mechanosensitive ion channels are the potassium channels [[KCNK2|TREK-1]] and [[KCNK4|TRAAK]], both of which are found in mammalian [[neuron]]s. |
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Recently, a new mechanosensitive ion channel family was cloned, with two mammalian members, [[PIEZO1]] and PIEZO2.<ref name="pmid20813920">{{cite journal | author = Coste B, Mathur J, Schmidt M, Earley TJ, Ranade S, Petrus MJ, Dubin AE, Patapoutian A | title = Piezo1 and Piezo2 are essential components of distinct mechanically activated cation channels | journal = Science | volume = 330 | issue = 6000 | pages = 55–60 | year = 2010 | month = October | pmid = 20813920 | pmc = 3062430 | doi = 10.1126/science.1193270 }}</ref> Both these channels are expressed in the lungs and bladder, organs with important mechanosensory functions. Piezo1 is also expressed in the skin, and in red blood cells, and its gain of function mutations cause hereditary xerocytosis.<ref name="pmid22529292">{{cite journal | author = Zarychanski R, Schulz VP, Houston BL, Maksimova Y, Houston DS, Smith B, Rinehart J, Gallagher PG | title = Mutations in the mechanotransduction protein PIEZO1 are associated with hereditary xerocytosis | journal = Blood | volume = 120 | issue = 9 | pages = 1908–15 | year = 2012 | month = August | pmid = 22529292 | doi = 10.1182/blood-2012-04-422253 }}</ref> Piezo2 is expressed in sensory neurons of the dorsal root and trigeminal ganglia indicating that it may play a role in touch sensation. Mutations in piezo2 are associated with a human disease named Distal Arthrogryposis.<ref name="pmid23487782">{{cite journal | author = Coste B, Houge G, Murray MF, Stitziel N, Bandell M, Giovanni MA, Philippakis A, Hoischen A, Riemer G, Steen U, Steen VM, Mathur J, Cox J, Lebo M, Rehm H, Weiss ST, Wood JN, Maas RL, Sunyaev SR, Patapoutian A | title = Gain-of-function mutations in the mechanically activated ion channel PIEZO2 cause a subtype of Distal Arthrogryposis | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 110 | issue = 12 | pages = 4667–72 | year = 2013 | month = March | pmid = 23487782 | doi = 10.1073/pnas.1221400110 }}</ref> |
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The bacterial MS channels are the best studied, and provide a paradigm of how a protein senses membrane stretch. They are involved in osmotic homeostasis, serving as 'emergency release valves' protecting the cell from acute decreases in osmotic environment. There are two families of bacterial MS channels: |
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* [[Large-conductance mechanosensitive channel]], [[Large-conductance mechanosensitive channel | MscL]] |
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* [[Small-conductance mechanosensitive channel]]s (MscS or YggB). The pressure threshold for MscS opening is 50% that of MscL.<ref name="Bass">{{cite journal | author = Bass RB, Strop P, Barclay M, Rees DC | title = Crystal structure of Escherichia coli MscS, a voltage-modulated and mechanosensitive channel | journal = Science | volume = 298 | issue = 5598 | pages = 1582–7 | year = 2002 | month = November | pmid = 12446901 | doi = 10.1126/science.1077945 }}</ref> |
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The MscS family is much larger and more variable in size and sequence than the MscL family. Much of the diversity in MscS proteins occurs in the size of the transmembrane regions, which ranges from three to eleven transmembrane helices, although the three C-terminal helices are conserved. |
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MscS folds as a homo-heptamer with a cylindrical shape, and can be divided into transmembrane and extramembrane regions: an N-terminal periplasmic region, a transmembrane region, and a C-terminal cytoplasmic region (middle and C-terminal domains). The transmembrane region forms a channel through the membrane that opens into a chamber enclosed by the extramembrane portion, the latter connecting to the cytoplasm through distinct portals.<ref name="Bass" /> |
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== See also == |
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*[[Mechanosensation]] |
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== References == |
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{{Reflist|35em}} |
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== External links == |
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*[http://pfam.sanger.ac.uk/family?entry=PF00924 Mechanosensitive ion channel family in Pfam] |
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* {{UMichOPM|protein|pdbid|2oau}} |
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[[Category:Transmembrane proteins]] |
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Latest revision as of 13:45, 18 August 2016
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