TRPM
TRPM is a family of transient receptor potential ion channels. Functional TRPM channels are believed to form tetramers. The TRPM family consists of eight different channels, TRPM1–TRPM8.
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 and TRPM5 are impermeable to calcium.
- TRPM3, TRPM6 and TRPM7 are highly permeable to both calcium and magnesium.
- TRPM2 is activated by ADP-ribose adenosine 5'-diphosphoribose and functions as a sensor of redox status in cells.
- TRPM4 and TRPM5 are activated by intracellular calcium.
- TRPM8 can be activated by low temperatures, menthol, eucalyptol and icilin.
Functions
Among the functional responsibilities of the TRPM channels are:- regulation of calcium oscillations after T cell activation and prevention of cardiac conduction disorders.
- modulation of insulin secretion and sensory transduction in taste cells .
- cold sensation.
- heat sensation and inflammatory pain.
- regulation of magnesium reabsorption in the kidneys and absorption in the intestines.
- regulation of cell adhesion.