obsolete transmembrane electron transfer carrier true GO:0022865 OBSOLETE. Enables electron flow across a biological membrane, from donors localized on one side of the membrane to acceptors localized on the other side. These systems contribute to or subtract from the membrane potential, depending on the direction of electron flow. They are therefore important to cellular energetics. molecular_function The reason for obsoletion is that the term does not represent a molecular function but rather a process.