9.B.238. The Uncharacterized Bacterial 5 TMS Protein-2 (UBP1) Family
This family consists of proteins with fairly uniform topologies with N-terminal transmembrane domains with 5 or 6 TMSs followed by C-terminal hydrophilic domains of variable sizes. Proteins from uncultured bacterial are much more similar to each other than to proteins from cultured bacteria. However, sensor histidine kinases with N-terminal integral membrane domains were found from cultured bacteria. The former were put into TC subfamily 9.B.238.1 with the latter being included in TC subfamily 9.B.238.2. The putative ABC transporters retrieved with low scores in the BLAST searches were included in ABC family 3.A.1.103, members 6, 7 and 8. Thus, some of the uncharacterized members of this family are probably sensor kinases, but some may be transporters. They are related to some members of TC family 9.B.259.2 which may also be histidine sensor kinases.