ATP synthase alpha/beta subunits

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A part of F1 ATP synthase complex: alpha, beta and gamma subunits (PDB 1bmf)

ATP synthase alpha/beta family, beta-barrel domain
Identifiers
Symbol	ATP-synt_ab_N
Pfam	PF02874
InterPro	IPR004100
PROSITE	PDOC00137
SCOP	1bmf
Available PDB structures: 1fx0B:23-95 1kmhB:23-95 1nvzA:6-73 1skyE:6-80 1e1rD:63-129 1bmfD:63-129 1nbmD:63-129 1cowF:63-129 1h8eE:63-129 1efrE:63-129 1h8hF:63-129 1w0kD:63-129 1e1qE:63-129 1w0jE:63-129 1e79E:63-129 1e16A:4-70 1e1iA:4-70 1v0iA:26-91 2bn9A:21-92

ATP synthase alpha/beta family, nucleotide-binding domain
Identifiers
Symbol	ATP-synt_ab
Pfam	PF00006
InterPro	IPR000194
PROSITE	PDOC00137
SCOP	1bmf
Available PDB structures: 1jvaA:273-746 1gppA:283-482 1vdeA:283-736 1um2D:273-287 1lwtA:283-736 1dfaA:283-736 1lwsA:283-736 1fx0B:151-372 1kmhB:151-372 1e1iA:126-348 1e16A:126-348 1e1rD:185-405 1bmfD:185-405 1nbmD:185-405 1cowF:185-405 1h8eE:185-405 1efrE:185-405 1h8hF:185-405 1w0kD:185-405 1e1qE:185-405 1w0jE:185-405 1e79E:185-405 1skyE:137-351 1nvzA:129-349 1v0iA:147-357 2bn9A:154-364

ATP synthase alpha/beta chain, C terminal domain
Identifiers
Symbol	ATP-synt_ab_C
Pfam	PF00306
InterPro	IPR000793
SCOP	1bmf
Available PDB structures: 1e79B:427-531 1w0jB:427-531 1h8eA:427-531 1h8hA:427-531 1efrA:427-531 1bmfB:427-531 1e1qB:427-531 1cowA:427-531 1e1rB:427-531 1w0kB:427-531 1nbmC:427-531 1skyB:376-480 1kmhA:377-495 1fx0A:377-495 1e16A:361-454 1e1iA:361-454 1nvzA:362-466

ATPases (or ATP synthases) are membrane-bound enzyme complexes/ion transporters that combine ATP synthesis and/or hydrolysis with the transport of protons across a membrane. ATPases can harness the energy from a proton gradient, using the flux of ions across the membrane via the ATPase proton channel to drive the synthesis of ATP.

Some ATPases work in reverse, using the energy from the hydrolysis of ATP to create a proton gradient.

There are different types of ATPases, which can differ in function (ATP synthesis and/or hydrolysis), structure (F-, V- and A-ATPases contain rotary motors) and in the type of ions they transport^[1]^[2].

F-ATPases (F1F0-ATPases) in mitochondria, chloroplasts and bacterial plasma membranes are the prime producers of ATP, using the proton gradient generated by oxidative phosphorylation (mitochondria) or photosynthesis (chloroplasts).
V-ATPases (V1V0-ATPases) are primarily found in eukaryotic vacuoles, catalysing ATP hydrolysis to transport solutes and lower pH in organelles.
A-ATPases (A1A0-ATPases) are found in Archaea and function like F-ATPases.
P-ATPases (E1E2-ATPases) are found in bacteria and in eukaryotic plasma membranes and organelles, and function to transport a variety of different ions across membranes.
E-ATPases are cell-surface enzymes that hydrolyse a range of nucleoside triphosphates, including extracellular ATP.

The alpha and beta (or A and B) subunits are found in the F1, V1, and A1 complexes of F-, V- and A-ATPases, respectively, as well as flagellar ATPase and the termination factor Rho. The F-ATPases (or F1F0-ATPases), V-ATPases (or V1V0-ATPases) and A-ATPases (or A1A0-ATPases) are composed of two linked complexes: the F1, V1 or A1 complex contains the catalytic core that synthesizes/hydrolyses ATP, and the F0, V0 or A0 complex that forms the membrane-spanning pore. The F-, V- and A-ATPases all contain rotary motors, one that drives proton translocation across the membrane and one that drives ATP synthesis/hydrolysis^[3]^[4].

In F-ATPases, there are three copies each of the alpha and beta subunits that form the catalytic core of the F1 complex, while the remaining F1 subunits (gamma, delta, epsilon) form part of the stalks. There is a substrate-binding site on each of the alpha and beta subunits, those on the beta subunits being catalytic, while those on the alpha subunits are regulatory. The alpha and beta subunits form a cylinder that is attached to the central stalk. The alpha/beta subunits undergo a sequence of conformational changes leading to the formation of ATP from ADP, which are induced by the rotation of the gamma subunit, itself is driven by the movement of protons through the F0 complex C subunit^[5].

In V- and A-ATPases, the alpha/A and beta/B subunits of the V1 or A1 complex are homologous to the alpha and beta subunits in the F1 complex of F-ATPases, except that the alpha subunit is catalytic and the beta subunit is regulatory.

The alpha/A and beta/B subunits can each be divided into three regions, or domains, centred around the ATP-binding pocket, and based on structure and function. The central domain contains the nucleotide-binding residues that make direct contact with the ADP/ATP molecule^[6].

[edit] Human proteins containing this domain

ATP5A1; ATP5B; ATP6V1A; ATP6V1B1; ATP6V1B2;

[edit] References

^ Muller V, Cross RL (2004). "The evolution of A-, F-, and V-type ATP synthases and ATPases: reversals in function and changes in the H+/ATP coupling ratio". FEBS Lett. 576 (1): 1-4. PMID 15473999.
^ Zhang X, Niwa H, Rappas M (2004). "Mechanisms of ATPases--a multi-disciplinary approach". Curr Protein Pept Sci 5 (2): 89-105. PMID 15078220.
^ Itoh H, Yoshida M, Yasuda R, Noji H, Kinosita K (2001). "Resolution of distinct rotational substeps by submillisecond kinetic analysis of F1-ATPase". Nature 410 (6831): 898-904. PMID 11309608.
^ Wilkens S, Zheng Y, Zhang Z (2005). "A structural model of the vacuolar ATPase from transmission electron microscopy". Micron 36 (2): 109-126. PMID 15629643.
^ Amzel LM, Bianchet MA, Leyva JA (2003). "Understanding ATP synthesis: structure and mechanism of the F1-ATPase (Review)". Mol. Membr. Biol. 20 (1): 27-33. PMID 12745923.
^ Chandler D, Wang H, Antes I, Oster G (2003). "The unbinding of ATP from F1-ATPase". Biophys. J. 85 (2): 695-706. PMID 12885621.