TRPM

TRPM is a family of transient receptor potential ion channels where the "M" stands for "melastatin".cite journal |author=Kraft R, Harteneck C |title=The mammalian melastatin-related transient receptor potential cation channels: an overview |journal=Pflugers Arch |volume= 451 |issue=1 |pages=204–11 |year=2005 |pmid= 15895246 |doi=10.1007/s00424-005-1428-0] Functional TRPM channels are believed to form tetramers.cite journal |author=Jiang LH |title=Subunit interaction in channel assembly and functional regulation of transient receptor potential melastatin (TRPM) channels |journal=Biochem Soc Trans |volume=35 |issue=1 |pages=86–8 |year=2007 |pmid= 17233608 |doi=10.1042/BST0350086]

Unlike the TRPC and TRPV sub-families, TRPM subunits do not contain N-terminal ankyrin repeat motifs but, rather, contain entire functional proteins in their C-termini. TRPM6 and TRPM7, for example, contain functional α-kinase segments, which are a type of serine/threonine-specific protein kinase.

Permeability and activation

The relative permeability of calcium and magnesium varies widely among TRPM channels.
* TRPM4/5 are impermeable to calcium.
* TRPM3/6/7 are highly permeable to both calcium and magnesium.

The mechanism of activation also varies greatly among TRPM channels.
* TRPM2 is activated by ADPRibose Adenosine 5'-diphosphoribose.
* TRPM2 is a sensor of redox status in cells.cite journal |author=Hara Y, Wakamori M, Ishii M, Maeno E, Nishida M, Yoshida T, Yamada H, Shimizu S, Mori E, Kudoh J, Shimizu N, Kurose H, Okada Y, Imoto K, Mori Y |title=LTRPC2 Ca2+-permeable channel activated by changes in redox status confers susceptibility to cell death |journal=Mol Cell |volume=9 |issue=1 |pages=163–73 |year=2002 |pmid= 11804595 |doi=10.1016/S1097-2765(01)00438-5]
* TRPM4/5 are activated by intracellular calcium.
* TRPM8, conversely, can be activated by low temperatures, menthol, eucalyptol and icilin.cite journal |author=Behrendt HJ, Germann T, Gillen C, Hatt H, Jostock R |title=Characterization of the mouse cold-menthol receptor TRPM8 and vanilloid receptor type-1 VR1 using a fluorometric imaging plate reader (FLIPR) assay |journal=Br. J. Pharmacol. |volume=141 |issue=4 |pages=737–45 |year=2004 |pmid=14757700 |doi=10.1038/sj.bjp.0705652] cite journal |author=Nilius B, Owsianik G, Voets T, Peters JA |title=Transient receptor potential cation channels in disease |journal=Physiol. Rev. |volume=87 |issue=1 |pages=165–217 |year=2007 |pmid=17237345 |doi=10.1152/physrev.00021.2006]

Functions

Among the functional responsibilities of the TRPM channels are:
* regulation of calcium oscillations after T cell activation (TRPM4). [cite journal |author=Launay P, Cheng H, Srivatsan S, Penner R, Fleig A, Kinet J.-P. |title=TRPM4 regulates calcium oscillations after T cell activation |journal=Science |volume=306 |pages=1374–77 |year=2004 |pmid=15550671 |doi=10.1126/science.1098845]
* sensory transduction in taste cells (TRPM5).
* regulation of magnesium reabsorption in the kidneys and absorption in the intestines (TRPM6).cite journal |author=Schlingmann KP, Weber S, Peters M, Niemann Nejsum L, Vitzthum H, Klingel K, Kratz M, Haddad E, Ristoff E, Dinour D, Syrrou M, Nielsen S, Sassen M, Waldegger S, Seyberth HW, Konrad M |title=Hypomagnesemia with secondary hypocalcemia is caused by mutations in TRPM6, a new member of the TRPM gene family |journal=Nat. Genet. |volume=31 |issue=2 |pages=166–70 |year=2002 |pmid=12032568 |doi=10.1038/ng889]
* regulation of cell adhesion (TRPM7). [cite journal |author=Su L-T., Agapito MA, Li M, Simonson WTN, Huttenlocher A, Habas R, Yue L, Runnels LW |title=TRPM7 regulates cell adhesion by controlling the calcium-dependent protease calpain |journal=J. Biol. Chem. |volume=281 |issue=16 |pages=11260–70 |year=2006 |pmid=16436382 |doi=10.1074/jbc.M512885200]

Genes

* TRPM1, TRPM2, TRPM3, TRPM4, TRPM5, TRPM6, TRPM7, TRPM8

References

External links

*MeshName|TRPM+Cation+Channels