DsbD gamma family; DsbD gamma is the C-terminal periplasmic domain of the bacterial protein DsbD. It contains a CXXC motif in a TRX fold and shuttles the reducing potential from the membrane domain (DsbD beta) to the N-terminal periplasmic domain (DsbD alpha). DsbD beta, a transmembrane domain comprising of eight helices, acquires its reducing potential from the cytoplasmic thioredoxin. DsbD alpha transfers the acquired reducing potential from DsbD gamma to target proteins such as the periplasmic protein disulphide isomerases, DsbC and DsbG. This flow of reducing potential from the cytoplasm through DsbD allows DsbC and DsbG to act as isomerases in the oxidizing environment of the bacterial periplasm. DsbD also transfers reducing potential from the cytoplasm to specific reductases in the periplasm which are involved in the maturation of cytochromes.