InterPro domain: IPR038662

This entry represents subunit C (also called subunit 9, or proteolipid) found in the F0 complex of F-ATPases. Ten C subunits form an oligomeric ring that makes up the F0 rotor. The flux of protons through the ATPase channel drives the rotation of the C subunit ring, which in turn is coupled to the rotation of the F1 complex gamma subunit rotor due to the permanent binding between the gamma and epsilon subunits of F1 and the C subunit ring of F0. The sequential protonation and deprotonation of Asp61 of subunit C is coupled to the stepwise movement of the rotor [ 1 ].

F1F0 ATP synthase subunit C is a mainly all-alpha protein with the helices arranged in an up-down bundle. The protein fold is a hairpin of two antiparallel helical segments connected by a short structured loop [ 2 ].

1. Mechanics of coupling proton movements to c-ring rotation in ATP synthase. FEBS Lett. 555, 29-34
2. Solution structure of the transmembrane H+-transporting subunit c of the F1F0 ATP synthase. Biochemistry 37, 8817-24