In yeast, the F_O complex E subunit appears to play an important role in supporting F-ATPase

F-ATPase

F-ATPase, also known as F-Type ATPase , is an ATPase found in bacterial plasma membranes, in mitochondrial inner membranes, and in chloroplast thylakoid membranes...

 dimerisation. This subunit is anchored to the inner mitochondrial membrane

Inner mitochondrial membrane

The mitochondrial inner membrane forms internal compartments known as cristae, which allow greater space for the proteins such as cytochromes to function properly and efficiently. The electron transport chain is located on the inner membrane of the mitochondria...

 via its N-terminal region, which is involved in stabilising subunits G and K of the F_O complex. The C-terminal region of subunit E is hydrophilic, protruding into the intermembrane space

Intermembrane space

The intermembrane space also known as IMS is the region between the inner membrane and the outer membrane of a mitochondrion or a chloroplast. The main function of the intermembrane space is oxidative phosphorylation....

 where it can also help stabilise the F-ATPase dimer

Protein dimer

In biochemistry, a dimer is a macromolecular complex formed by two, usually non-covalently bound, macromolecules like proteins or nucleic acids...

complex.

Further reading