Review: "Pyrophosphate and pyrophosphatases in plants, their involvement in stress responses and their possible relationship to secondary metabolism".

Pyrophosphate (PPi) is produced as byproduct of biosynthesis in the cytoplasm, nucleus, mitochondria and chloroplast, or in the tonoplast and Golgi by membrane-bound H-pumping pyrophosphatases (PPv). Inorganic pyrophosphatases (E.C.

Evidence for a non-overlapping subcellular localization of the family I isoforms of soluble inorganic pyrophosphatase in Arabidopsis thaliana.

Pyrophosphate is a byproduct of macromolecular biosynthesis and its degradation gives a thermodynamic impulse to cell growth. Soluble inorganic pyrophosphatases (PPa) are present in all living cells, but in plants and other Eukaryotes membrane-bound H+-pumping pyrophosphatases may compete with these soluble counterparts for the substrate. In Arabidopsis thaliana there are six genes encoding for classic family I PPa isoforms, five cytoplasmic, and one considered to be organellar.