{PDOC00420}
{PS00449; ATPASE_A}
{BEGIN}
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* ATP synthase a subunit signature *
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ATP synthase (proton-translocating ATPase) (EC 3.6.3.14) [1,2]  is a component
of the cytoplasmic membrane of eubacteria, the inner membrane of mitochondria,
and the thylakoid membrane of chloroplasts.  The ATPase complex is composed of
an oligomeric  transmembrane  sector, called CF(0),  which acts  as  a  proton
channel, and a catalytic core, termed coupling factor CF(1).

The CF(0) a subunit, also called protein 6,  is  a key component of the proton
channel; it  may  play  a  direct  role  in  translocating  protons across the
membrane. It  is  a  highly  hydrophobic  protein  that  has been predicted to
contain 8 transmembrane regions [3].

Sequence comparison of a subunits from all available sources reveals  very few
conserved regions.  The  best conserved region is located in what is predicted
to be    the fifth transmembrane domain.  This region contains three perfectly
conserved residues:  an  arginine,  a  leucine  and an asparagine. Mutagenesis
experiments carried  out  in Escherichia coli [4] have shown that the arginine
is necessary  for  proton  translocation  and  that its replacement by another
amino acid  results  in  loss of ATPase activity. We selected this region as a
signature pattern.

-Consensus pattern: [STAGN]-{E}-[STAG]-[LIVMF]-R-L-{LP}-[SAGV]-N-[LIVMT]
                    [R is important for proton translocation]
-Sequences known to belong to this class detected by the pattern: ALL,  except
 for the Mytilus edulis and Trypanosoma brucei subunits.
-Other sequence(s) detected in Swiss-Prot: 8.
-Last update: December 2004 / Pattern and text revised.

[ 1] Futai M., Noumi T., Maeda M.
     "ATP synthase (H+-ATPase): results by combined biochemical and
     molecular biological approaches."
     Annu. Rev. Biochem. 58:111-136(1989).
     PubMed=2528322; DOI=10.1146/annurev.bi.58.070189.000551
[ 2] Senior A.E.
     "ATP synthesis by oxidative phosphorylation."
     Physiol. Rev. 68:177-231(1988).
     PubMed=2892214
[ 3] Lewis M.J., Chang J.A., Simoni R.D.
     "A topological analysis of subunit alpha from Escherichia coli
     F1F0-ATP synthase predicts eight transmembrane segments."
     J. Biol. Chem. 265:10541-10550(1990).
     PubMed=2162353
[ 4] Cain B.D., Simoni R.D.
     "Proton translocation by the F1F0ATPase of Escherichia coli. Mutagenic
     analysis of the a subunit."
     J. Biol. Chem. 264:3292-3300(1989).
     PubMed=2536742

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