Complex V, also called F1F0ATPase or ATP synthase, is responsible for ATP production in oxidative phosphorylation and can work in reverse as a proton pumping ATPase. The enzyme was thought to be localized exclusively to mitochondria. However, it has recently been identified on the plasma membrane of several cell types including hepatocytes where it functions as the HDL receptor, on endothelial cells where it may act as the angiostatin receptor, and on the surface of cancer cells. The enzyme in mammals is composed of 17 subunits, five of which make up the easily detached F1. The remainder subunits are components of two stalk domains and the proton pumping F0 part of the machinery. Two of the subunits of the F0 part are encoded on mitochondrial DNA while the other subunits are nuclear encoded. Mutations in the mitochondrial-encoded subunits of ATP synthase (Complex V) cause OXPHOS disease.