9.B.344. The Uncharacterized Archaeal 4 TMS Protein (UA4P) Family
The proteins of the UA4P family are usually about 200 aas in length and have 4 TMSs often in a 1 +2 + 1 TMS arrangement. They are found exclusively in archaea, mostly in Lokiarchaeota and Methanomassiliicoccus species. In the latter organisms, there are both 4 and 8 TMS proteins. In the latter, the two halves are both homologous to the 4 TMS proteins. This provides evidence that these proteins may be transporters that function as homodimers of two 4 TMS proteins or as monomers of the 8 TMS proteins.