TCDB is operated by the Saier Lab Bioinformatics Group
5: Transmembrane Electron Carriers

Transmembrane electron flow systems influence the energetics of a cell or organelle, influencing the magnitude of the membrane potential. Systems that catalyze electron flow across a biological membrane, from donors localized to one side of the membrane to acceptors localized on the other side, are grouped into TC category 5. These systems contribute to or subtract from the membrane potential, depending on the direction of electron flow. They are therefore important to cellular energetics. 

These include:

5.A Transmembrane 2-Electron Transfer Carriers

5.B Transmembrane 1-Electron Transfer Carriers