F-ATPase, also known as F-Type ATPase, is an

ATPase ATPases (, Adenosine 5'-TriPhosphatase, adenylpyrophosphatase, ATP monophosphatase, triphosphatase, SV40 T-antigen, ATP hydrolase, complex V (mitochondrial electron transport), (Ca2+ + Mg2+)-ATPase, HCO3−-ATPase, adenosine triphosphatase) are ...

/ synthase found in bacterial

plasma membrane The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment (t ...

s, in mitochondrial inner membranes (in

oxidative phosphorylation Oxidative phosphorylation (UK , US ) or electron transport-linked phosphorylation or terminal oxidation is the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing chemical energy in order to produce adenosine tri ...

, where it is known as Complex V), and in

chloroplast A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in ...

thylakoid membranes Thylakoids are membrane-bound compartments inside chloroplasts and cyanobacteria. They are the site of the light-dependent reactions of photosynthesis. Thylakoids consist of a thylakoid membrane surrounding a thylakoid lumen. Chloroplast thyl ...

. It uses a

proton A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...

gradient to drive ATP synthesis by allowing the passive flux of protons across the membrane down their electrochemical gradient and using the energy released by the transport reaction to release newly formed ATP from the active site of F-ATPase. Together with

V-ATPase Vacuolar-type ATPase (V-ATPase) is a highly conserved evolutionarily ancient enzyme with remarkably diverse functions in eukaryotic organisms. V-ATPases acidify a wide array of intracellular organelles and pumps protons across the plasma ...

s and A-ATPases, F-ATPases belong to superfamily of related rotary

s. F-ATPase consists of two domains: * the F_o domain, which is integral in the membrane and is composed of 3 different types of integral proteins classified as a, b and c. * the F₁, which is peripheral (on the side of the membrane that the protons are moving into). F₁ is composed of 5 polypeptide units α3β3γδε that bind to the surface of the F_o domain. F-ATPases usually work as ATP synthases instead of ATPases in cellular environments. That is to say, it usually makes ATP from the proton gradient instead of working in the other direction like V-ATPases typically do. They do occasionally revert as ATPases in bacteria.

Structure

F_o-F₁ particles are mainly formed of

polypeptides Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. A p ...

. The F₁-particle contains 5 types of polypeptides, with the composition-ratio—3α:3β:1δ:1γ:1ε. The F_o has the 1a:2b:12c composition. Together they form a rotary motor. As the protons bind to the subunits of the F_o domains, they cause parts of it to rotate. This rotation is propagated by a 'camshaft' to the F₁ domain. ADP and Pi (inorganic phosphate) bind spontaneously to the three β subunits of the F₁ domain, so that every time it goes through a 120° rotation ATP is released (rotational catalysis). The F_o domains sits within the membrane, spanning the phospholipid bilayer, while the F₁ domain extends into the cytosol of the cell to facilitate the use of newly synthesized ATP. The Bovine Mitochondrial F₁-ATPase Complexed with the

inhibitor protein The inhibitor protein (IP) is situated in the mitochondrial matrix and protects the cell against rapid ATP hydrolysis during momentary ischaemia Ischemia American and British English spelling differences#ae and oe, or ischaemia is a restric ...

If1 is commonly cited in the relevant literature. Examples of its use may be found in many cellular fundamental metabolic activities such as

acidosis Acidosis is a process causing increased acidity in the blood and other body tissues (i.e., an increase in hydrogen ion concentration). If not further qualified, it usually refers to acidity of the blood plasma. The term ''acidemia'' describes t ...

and

alkalosis Alkalosis is the result of a process reducing hydrogen ion concentration of arterial blood plasma (alkalemia). In contrast to acidemia (serum pH 7.35 or lower), alkalemia occurs when the serum pH is higher than normal (7.45 or higher). Alkalosis i ...

and respiratory gas exchange. The o in the F_o stands for

oligomycin Oligomycins are macrolides created by ''Streptomyces'' that can be poisonous to other organisms. Function They have use as antibiotics. Oligomycin A is an inhibitor of ATP synthase. In oxidative phosphorylation research, it is used to prevent ...

, because oligomycin is able to inhibit its function.

N-ATPase

N-ATPases are a group of F-type ATPases without a delta/OSCP subunit, found in bacteria and a group of archaea via horizontal gene transfer. They transport sodium ions instead of protons and tend to hydrolyze ATP. They form a distinct group that is further apart from usual F-ATPases than A-ATPases are from V-ATPases.

References

{{ATPase Membrane proteins