TRPMLs, also termed mucolipins, are members of the TRP channels. In mammals, three TRPMLs are known to date (TRPML1-3 or MCOLN1-3). They are all localized to endolysosomes, although when over expressed in heterologous systems, TRPML3 is found on the plasma membrane. These channels are Ca2+ permeable and display inward rectifying current properties. Like all members of this family, TRPMLs have six transmembrane domains and intracellular N- and C-termini (relatively short tails compared to other members). They are characterized by an exceptionally large extracellular (luminal) loop between transmembrane domains 1 and 2, and N-glycosylation sites are present in the first extracellular (luminal) loop.