The MENTAL or MLN64 NH₂-terminal domain is a membrane-spanning domain that is conserved in two late endosomal

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...

 proteins in vertebrates, MLN64

MLN64

StAR-related lipid transfer domain protein 3 also known as metastatic lymph node 64 protein is a late endosomal integral membrane protein involved in cholesterol transport.-Function:...

 and MENTHO

STARD3NL

MENTHO or STARD3 N-terminal like protein is an integral membrane protein of unknown function. As the alternate name implies, MENTHO, short for "MLN64 N-terminal homologue", contains a region in its N-terminus similar to that found in STARD3, also known as MLN64, but lacks the StAR-related transfer...

. The domain is 170 amino acids long.

Current data indicates that this domain allows for dimerization

Protein dimer

In biochemistry, a dimer is a macromolecular complex formed by two, usually non-covalently bound, macromolecules like proteins or nucleic acids...

 between MLN64 and MENTHO molecules and with themselves. The domain may also direct cholesterol

Cholesterol

Cholesterol is a complex isoprenoid. Specifically, it is a waxy steroid of fat that is produced in the liver or intestines. It is used to produce hormones and cell membranes and is transported in the blood plasma of all mammals. It is an essential structural component of mammalian cell membranes...

transport.