?cl38906: ATP-synt_Fo_Vo_Ao_c Superfamily
ATP synthase, membrane-bound Fo/Vo/Ao complexes, subunit c Subunit c of the Fo/Vo/Ao complex is the main transmembrane subunit of F-, V- or A-type family of ATP synthases with rotary motors. These ion-transporting rotary ATP synthases are composed of two linked multi-subunit complexes: the F1, V1, and A1 complexes contains three copies each of the alpha and beta subunits that form the soluble catalytic core, which is involved in ATP synthesis/hydrolysis, and the Fo, Vo, or Ao (oligomycin sensitive) complex that forms the membrane-embedded proton pore. The F-ATP synthases (also called FoF1-ATPases) are found in the inner membranes of eukaryotic mitochondria, in the thylakoid membranes of chloroplasts, or in the plasma membranes of bacteria. F-ATPases are the primary producers of ATP, using the proton gradient generated by oxidative phosphorylation (mitochondria) or photosynthesis (chloroplasts). Alternatively, under conditions of low driving force, ATP synthases function as ATPases, thus generating a transmembrane proton or Na(+) gradient at the expense of energy derived from ATP hydrolysis. The A-ATP synthase (AoA1-ATPases) is exclusively found in archaea and function like F-ATP synthase. Structurally, however, the A-ATP synthase is more closely related to the V-ATP synthase (vacuolar VoV1-ATPase), which is a proton-translocating ATPase responsible for acidification of eukaryotic intracellular compartments and for ATP synthesis in archaea and some eubacteria. Collectively, F-, V-, and A-type synthases can function in both ATP synthesis and hydrolysis modes.
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