1. EWING, N.E., WIMMERS, L.E., MEYER, D.J., CHETELAT, R.T. AND BENNETT, A.B.
Molecular cloning of tomato plasma membrane H+-ATPase.
PLANT PHYSIOL. 94(2) 1874-1881 (1990).
2. HARPER, J.F., MANNEY, L., DEWITT, N.D., YOO, M.H. AND SUSSMAN, M.R.
The Arabidopsis thaliana plasma membrane H+-ATPase multigene family -
genomic sequence and expression of a third isoform.
J.BIOL.CHEM. 265(23) 13601-13608 (1990).
3. FAGAN, M.J. AND SAIER, M.H.
P-type ATPases of eukaryotes and bacteria: sequence analyses and
construction of phylogenetic trees.
J.MOL.EVOL. 38 57-99 (1994).
4. ADDISON, R.
Primary structure of the Neurospora plasma membrane H+-ATPase deduced from
the gene sequence. Homology to the Na+/K+-ATPases, Ca2+-ATPases, and
J.BIOL.CHEM. 261(32) 4896-4901 (1986).
H+-Transporting ATPases (proton pumps) are the main ion pumps in the plasma
membrane and play a central role  in the physiology and bioenergetics of
plant cells. They are the primary active transporters of the plasma
membrane and are responsible for generating the membrane potential that
drives translocation of cations, amino-acids, sugars, and hormones, whilst
also contributing to the maintenance of intracellular and extracellular
pH and cell turgor .
Proton pumps are members of the P-type (or E1-E2-type) cation-transporting
ATPase superfamily, which has evolved from a common ancestral gene . The
sequences are believed to contain 8-10 transmembrane helices, some of which
are well conserved throughout the superfamily. They may thus all operate via
a similar mechanism, with an aspartylphosphoryl enzyme intermediate 
being formed during the catalytic cycle.
HATPASE is a 5-element fingerprint that provides a signature for the
H+-transporting ATPases. The fingerprint was derived from an initial
alignment of 6 sequences: the motifs were drawn from conserved regions in
the C-terminal half of the alignment. Two iterations on OWL19.1 were
required to reach convergence, at which point a true set comprising 20
sequences was identified. Several partial matches were also found, largely
subsets of other cation-transporting ATPases: calcium-transporting ATPases
in general match only motifs 2-4, and sodium/potassium-transporting ATPases
tend to match motifs 2 and 3 (various potassium-transporting, magnesium-
transporting, and plasma membrane isoforms of calcium-transporting ATPases
also match just 2 motifs).
An update on SPTR37_9f identified a true set of 40 sequences, and 5