TMEM163

Previously, it was shown that purified rodent Tmem163 protein reconstituted in liposomes forms a dimer and transports zinc in a proton-dependent manner. It was also shown that Tmem163's ability to bind and transport zinc becomes inactivated upon alanine substitution of two species-conserved aspartate residues at positions 123 and 127. Thus, the data indicate that these double aspartate residues are zinc binding sites, but that they do not affect Tmem163 dimerization. Note, however, that this particular study did not address the question of whether the protein serves to transport zinc in or out of living cells. TMEM163 may play a crucial role in cellular zinc homeostasis by extruding cytoplasmic zinc ions to the extracellular environment. Noteworthy is that TMEM163 is unique in that it has a short C-terminus region, whereas the human ZNT family of efflux transporters have typically long C-terminus regions. Despite such structural difference, data from both functional and phylogenetic studies of TMEM163 suggest that it should now be referred to as ZNT11 protein and its gene named as SLC30A11.