TRPM
Encyclopedia
TRPM is a family of transient receptor potential ion channel
s (the "M" stands for "melastatin"). Functional TRPM channels are believed to form tetramers.
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
.
The mechanism of activation also varies greatly among TRPM channels.
Ion channel
Ion channels are pore-forming proteins that help establish and control the small voltage gradient across the plasma membrane of cells by allowing the flow of ions down their electrochemical gradient. They are present in the membranes that surround all biological cells...
s (the "M" stands for "melastatin"). Functional TRPM channels are believed to form tetramers.
Unlike the TRPC
TRPC
TRPC is a family of transient receptor potential cation channels in animals.TRPC channels form the subfamily of channels in human most closely related to drosophila TRP channels. In terms of structure, this family possesses a number of similar characteristics...
and TRPV
TRPV
TRPV is a family of transient receptor potential ion channels. These channels are selective for calcium and magnesium over sodium ions. Like other members of the TRP superfamily, TRPV channels can be activated through seemingly disparate mechanisms...
sub-families, TRPM subunits do not contain N-terminal ankyrin repeat
Ankyrin repeat
The ankyrin repeat is a 33-residue motif in proteins consisting of two alpha helices separated by loops, first discovered in signaling proteins in yeast Cdc10 and Drosophila Notch. Ankyrin repeats mediate protein–protein interactions and are among the most common structural motifs in known proteins...
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
Serine/threonine-specific protein kinase
Serine/threonine protein kinases phosphorylate the OH group of serine or threonine .At least 125 of the 500+ human protein kinases are serine/threonine kinases .-Regulation:...
.
Permeability and activation
The relative permeability of calcium and magnesium varies widely among TRPM channels.- TRPM4TRPM4Transient receptor potential cation channel subfamily M member 4 , also known as melastatin-4, is a protein that in humans is encoded by the TRPM4 gene....
and TRPM5TRPM5Transient receptor potential cation channel subfamily M member 5 , also known as long transient receptor potential channel 5 is a protein that in humans is encoded by the TRPM5 gene....
are impermeable to calcium. - TRPM3TRPM3Transient receptor potential cation channel subfamily M member 3 is a protein that in humans is encoded by the TRPM3 gene.TRPM3 was shown to be activated by the neurosteroid pregnenolone sulphate in pancreatic beta cell. The activation causes calcium influx and subsequent insulin release, therefore...
, TRPM6TRPM6TRPM6 is a transient receptor potential ion channel associated with hypomagnesemia with secondary hypocalcemia....
and TRPM7TRPM7Transient receptor potential cation channel, subfamily M, member 7, also known as TRPM7, is a human gene encoding a protein of the same name.- Function :...
are highly permeable to both calcium and magnesium.
The mechanism of activation also varies greatly among TRPM channels.
- TRPM2TRPM2Transient receptor potential cation channel, subfamily M, member 2, also known as TRPM2, is a protein that in humans is encoded by the TRPM2 gene.-Function:...
is activated by ADP-ribose Adenosine 5'-diphosphoribose and functions as a sensor of redox status in cells. - TRPM4TRPM4Transient receptor potential cation channel subfamily M member 4 , also known as melastatin-4, is a protein that in humans is encoded by the TRPM4 gene....
and TRPM5TRPM5Transient receptor potential cation channel subfamily M member 5 , also known as long transient receptor potential channel 5 is a protein that in humans is encoded by the TRPM5 gene....
are activated by intracellular calcium. - TRPM8TRPM8Transient receptor potential cation channel subfamily M member 8 , also known as the cold and menthol receptor 1 , is a protein that in humans is encoded by the TRPM8 gene.-Function:...
, conversely, can be activated by low temperatures, mentholMentholMenthol is an organic compound made synthetically or obtained from peppermint or other mint oils. It is a waxy, crystalline substance, clear or white in color, which is solid at room temperature and melts slightly above. The main form of menthol occurring in nature is -menthol, which is assigned...
, eucalyptolEucalyptolEucalyptol is a natural organic compound which is a colorless liquid. It is a cyclic ether and a monoterpenoid.Eucalyptol is also known by a variety of synonyms: 1,8-cineol, 1,8-cineole, limonene oxide, cajeputol, 1,8-epoxy-p-menthane, 1,8-oxido-p-menthane, eucalyptol, eucalyptole,...
and icilinIcilinIcilin is a synthetic super-agonist of the transient receptor potential M8 ion channel. Although structurally not related with menthol it produces an extreme sensation of cold both in humans and animals. It is almost 200 times more potent than menthol and 2.5 times more efficacious. Despite their...
.
Functions
Among the functional responsibilities of the TRPM channels are:- regulation of calcium oscillations after T cell activation (TRPM4TRPM4Transient receptor potential cation channel subfamily M member 4 , also known as melastatin-4, is a protein that in humans is encoded by the TRPM4 gene....
). - sensory transduction in taste cells (TRPM5TRPM5Transient receptor potential cation channel subfamily M member 5 , also known as long transient receptor potential channel 5 is a protein that in humans is encoded by the TRPM5 gene....
). - cold sensation (TRPM8TRPM8Transient receptor potential cation channel subfamily M member 8 , also known as the cold and menthol receptor 1 , is a protein that in humans is encoded by the TRPM8 gene.-Function:...
) - regulation of magnesium reabsorption in the kidneys and absorption in the intestines (TRPM6TRPM6TRPM6 is a transient receptor potential ion channel associated with hypomagnesemia with secondary hypocalcemia....
). - regulation of cell adhesion (TRPM7TRPM7Transient receptor potential cation channel, subfamily M, member 7, also known as TRPM7, is a human gene encoding a protein of the same name.- Function :...
).