Editing ATPase (section)

==Mechanism==
ATPase (also called F<sub>0</sub>F<sub>1</sub>-ATP Synthase) is a charge-transferring complex that catalyzes ATP to perform ATP synthesis by moving ions through the membrane.<ref name=":0" />

The coupling of ATP hydrolysis and transport is a chemical reaction in which a fixed number of solute molecules are transported for each ATP molecule hydrolyzed; for the Na<sup>+</sup>/K<sup>+</sup> exchanger, this is three Na<sup>+</sup> ions out of the cell and two K+ ions inside per ATP molecule hydrolyzed.

Transmembrane ATPases make use of ATP's chemical potential energy by performing mechanical work: they transport solutes in the opposite direction of their thermodynamically preferred direction of movement—that is, from the side of the membrane with low concentration to the side with high concentration. This process is referred to as [[active transport]].

For instance, inhibiting vesicular H<sup>+</sup>-ATPases would result in a rise in the pH within vesicles and a drop in the pH of the cytoplasm.

All of the ATPases share a common basic structure. Each rotary ATPase is composed of two major components: F<sub>0</sub>/A<sub>0</sub>/V<sub>0</sub> and F<sub>1</sub>/A<sub>1</sub>/V<sub>1</sub>. They are connected by 1-3 stalks to maintain stability, control rotation, and prevent them from rotating in the other direction. One stalk is utilized to transmit torque.<ref>{{cite journal | vauthors = Hahn A, Parey K, Bublitz M, Mills DJ, Zickermann V, Vonck J, Kühlbrandt W, Meier T | display-authors = 6 | title = Structure of a Complete ATP Synthase Dimer Reveals the Molecular Basis of Inner Mitochondrial Membrane Morphology | journal = Molecular Cell | volume = 63 | issue = 3 | pages = 445–456 | date = August 2016 | pmid = 27373333 | doi = 10.1016/j.molcel.2016.05.037 | doi-access = free | pmc = 4980432 }}</ref> The number of peripheral stalks is dependent on the type of ATPase: F-ATPases have one, A-ATPases have two, and V-ATPases have three. The F<sub>1</sub> catalytic domain is located on the N-side (negative-side) of the membrane and is involved in the synthesis and degradation of ATP and is involved in [[oxidative phosphorylation]]. The F<sub>0</sub> transmembrane domain is involved in the movement of ions across the membrane.<ref name=":0">{{cite journal | vauthors = Calisto F, Sousa FM, Sena FV, Refojo PN, Pereira MM | title = Mechanisms of Energy Transduction by Charge Translocating Membrane Proteins | journal = Chemical Reviews | volume = 121 | issue = 3 | pages = 1804–1844 | date = February 2021 | pmid = 33398986 | doi = 10.1021/acs.chemrev.0c00830 | doi-access = free }}</ref>

The bacterial [[ATP synthase|F<sub>0</sub>F<sub>1</sub>-ATPase]] consists of the soluble F<sub>1</sub> domain and the transmembrane F<sub>0</sub> domain, which is composed of several subunits with varying stoichiometry. There are two subunits, γ, and ε, that form the central stalk and they are linked to F<sub>0</sub>. F<sub>0</sub> contains a c-subunit oligomer in the shape of a ring (c-ring). The α subunit is close to the subunit b<sub>2</sub> and makes up the stalk that connects the transmembrane subunits to the α3β3 and δ subunits. F-ATP synthases are identical in appearance and function except for the mitochondrial F<sub>0</sub>F<sub>1</sub>-ATP synthase, which contains 7-9 additional subunits.<ref name=":0" />

The [[electrochemical potential]] is what causes the c-ring to rotate in a clockwise direction for ATP synthesis. This causes the central stalk and the catalytic domain to change shape. Rotating the c-ring causes three ATP molecules to be made, which then causes H<sup>+</sup> to move from the P-side (positive-side) of the membrane to the N-side (negative-side) of the membrane. The counterclockwise rotation of the c-ring is driven by ATP hydrolysis and ions move from the N-side to the P-side, which helps to build up electrochemical potential.<ref name=":0" />