TCDB is operated by the Saier Lab Bioinformatics Group

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.

References associated with 9.B.238 family:

Aguilar, P.S., A.M. Hernandez-Arriaga, L.E. Cybulski, A.C. Erazo, and D. de Mendoza. (2001). Molecular basis of thermosensing: a two-component signal transduction thermometer in Bacillus subtilis. EMBO. J. 20: 1681-1691. 11285232
Albanesi, D., M.C. Mansilla, and D. de Mendoza. (2004). The membrane fluidity sensor DesK of Bacillus subtilis controls the signal decay of its cognate response regulator. J. Bacteriol. 186: 2655-2663. 15090506
Almada, J.C., A. Bortolotti, J.M. Ruysschaert, D. de Mendoza, M.E. Inda, and L.E. Cybulski. (2021). Interhelical H-Bonds Modulate the Activity of a Polytopic Transmembrane Kinase. Biomolecules 11:. 34201916
Cybulski, L.E., D. Albanesi, M.C. Mansilla, S. Altabe, P.S. Aguilar, and D. de Mendoza. (2002). Mechanism of membrane fluidity optimization: isothermal control of the Bacillus subtilis acyl-lipid desaturase. Mol. Microbiol. 45: 1379-1388. 12207704
Hunger, K., C.L. Beckering, and M.A. Marahiel. (2004). Genetic evidence for the temperature-sensing ability of the membrane domain of the Bacillus subtilis histidine kinase DesK. FEMS Microbiol. Lett. 230: 41-46. 14734164