TRPML comprises a group of three evolutionary related proteins that belongs to the large family of transient receptor potential

Transient receptor potential

Transient receptor potential channels are a group of ion channels located mostly on the plasma membrane of numerous human and animal cell types. There are about 28 TRP channels that share some structural similarity to each other...

 ion channel

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 three proteins TRPML1, TRPML2 and TRPML3 are encoded by the mucolipin-1 (MCOLN1), mucolipin-2 (MCOLN2

MCOLN2

Mucolipin-2 also known as TRPML2 is a protein that in humans is encoded by the MCOLN2 gene...

) and mucolipin-3 (MCOLN3

MCOLN3

Mucolipin-3 also known as TRPML3 is a protein that in humans is encoded by the MCOLN3 gene. It is a member of the small family of the TRPML channels, a subgroup of the large protein family of TRP ion channels.-Gene:In human, the MCOLN3 gene resides on the short arm of chromosome 1 at 1p22.3...

) genes, respectively.

The three members of the TRPML ("ML" for mucolipin) sub-family are not extremely well characterized. TRPML1

Mucolipin-1

Mucolipin-1 also known as TRPML1 is a protein that in humans is encoded by the MCOLN1 gene. It is a member of the small family of the TRPML channels, a subgroup of the large protein family of TRP ion channels.TRPML1 is a 65 kDa protein associated with mucolipidosis type IV...

 is known to be localized in late endosome

Endosome

In biology, an endosome is a membrane-bound compartment inside eukaryotic cells. It is a compartment of the endocytic membrane transport pathway from the plasma membrane to the lysosome. Molecules internalized from the plasma membrane can follow this pathway all the way to lysosomes for...

s. This subunit also contains a lipase domain between its S1 and S2 segments. While the function of this domain is unknown it has been proposed that it is involved in channel regulation. Physiological studies have described TRPML1 channels as proton

Proton

The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....

 leak channels in lysosome

Lysosome

thumb|350px|Schematic of typical animal cell, showing subcellular components. [[Organelle]]s: [[nucleoli]] [[cell nucleus|nucleus]] [[ribosomes]] [[vesicle |vesicle]] rough [[endoplasmic reticulum]]...

s responsible for preventing these organelles from becoming too acidic. TRPML2

MCOLN2

Mucolipin-2 also known as TRPML2 is a protein that in humans is encoded by the MCOLN2 gene...

 and TRPML3

MCOLN3

Mucolipin-3 also known as TRPML3 is a protein that in humans is encoded by the MCOLN3 gene. It is a member of the small family of the TRPML channels, a subgroup of the large protein family of TRP ion channels.-Gene:In human, the MCOLN3 gene resides on the short arm of chromosome 1 at 1p22.3...

 more poorly characterized than TRPML1.

Deficiencies can lead to enlarged vesicles.