Vacuolar H(+)-translocating pyrophosphatases: a new category of ion translocase.
The membrane surrounding the central vacuole of plant cells contains an H(+)-translocating ATPase (H(+)-ATPase) and an H(+)-translocating inorganic pyrophosphatase (H(+)-PPase). Both enzymes are abundant and ubiquitous in plants but the H(+)-PPase is unusual in its exclusive use of inorganic pyrophosphate (PPi) as an energy source. The lack of sequence identity between the vacuolar H(+)-PPase and any other characterized ion pump implies a different evolutionary origin for this translocase. The existence of the vacuolar H(+)-PPase, in conjunction with increasing recognition of PPi as a key metabolite in plant systems, necessitates reconsideration of ATP as the primary energy source for membrane transport in plant cells.
Rea
P A
PA
Department of Biology, University of Pennsylvania, Philadelphia 19104.
Kim
Y
Y
Sarafian
V
V
Poole
R J
RJ
Davies
J M
JM
Sanders
D
D
D000595:Amino Acid Sequence; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D011756:Diphosphates / Q000378:metabolism*; D008969:Molecular Sequence Data; D010944:Plants / Q000378:metabolism; D017494:Proton Pumps; D006180:Proton-Translocating ATPases; D014617:Vacuoles / Q000378:metabolism*
D011756:Diphosphates; D017494:Proton Pumps; D006180:Proton-Translocating ATPases