Molecular cloning of cDNA for vacuolar membrane proton-translocating inorganic pyrophosphatase in Hordeum vulgare.

We obtained a cDNA clone(PP10) for the vacuolar membrane proton-translocating inorganic pyrophosphatase from barley roots by immunoscreening. The nucleotide sequence contained a 2308 bp open reading frame capable of coding for a polypeptide with 761 amino acids (M(r) 79,841). The polypeptide is highly hydrophobic and 12 membrane-spanning regions are deduced from the hydropathic evaluation. The characteristic cluster of the basic and acidic residues is observed in the hydrophilic segment. A consensus sequence with the dicyclohexyl-carbodiimide binding subunits of FOF1-type and vacuolar-type H(+)-ATPase is also observed in the membrane-spanning domain 5. Comparison of the deduced amino acid sequence with that of pyrophosphatase cDNA from Arabidopsis thaliana revealed 85.8% homology.