The enzyme ATP synthase is an integral membrane protein. What is its function, and why proper functioning depend on it being located in a membrane? 2) In what membrane is it located in bacterial cells? 3) In what membrane is it located in your cells? Solution Like other enzymes, the activity of F1FO ATP synthase is reversible. Large-enough quantities of ATP cause it to create a transmembrane proton gradient, this is used by fermenting bacteria that do not have an electron transport chain, but rather hydrolyze ATP to make a proton gradient, which they use to drive flagella and the transport of nutrients into the cell. Its proper functioning depends on being in membrane due to the fact that it is essential to maintain the proton gradient which is possible only if it is located in a barrier like membranes..