5.B.11.1.1
Pentameric transmembrane electron flow carrier complex, TmcA₂BCD.  TmcA is an acidic periplasmic cytochrome c₃ of 126 aas and 0 TMSs anchored  to TmcC, TmcB is a ferridoxin/4Fe4S complex protein of 439 aas and 0 TMSs on the cytoplasmic side of the membrane, TmcC is a transmembrane protein of 219 aas and 5 TMSs, and TmcD is a cytochrome protein of 408 aas and 0 TMSs anchored to TmcC on the cytoplasmic side of the membrane.  This complex trasfers electrons resulting from the periplasmic oxidation of H₂ to the cytoplasmic reduction of sulfate (Pereira et al. 2006). TmcA shows weak similarity to a constituent of 5.B.3.1.1, TmcB shows similarity to a constituent of 3.D.7.1.1 and TmcC shows weak similarity to a constituent of 5.A.3.1.2, but TmcD does not show similarity to consitutents of other systems in TCDB.