TRPM

TRPM is a family of transient receptor potential ion channels (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 &alpha;-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.

The mechanism of activation also varies greatly among TRPM channels.
 * 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, conversely, 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 (TRPM4).
 * sensory transduction in taste cells (TRPM5).
 * cold sensation (TRPM8)
 * regulation of magnesium reabsorption in the kidneys and absorption in the intestines (TRPM6).
 * regulation of cell adhesion (TRPM7).

Genes

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