A vacuolar H+-pyrophosphatase in Acetabularia acetabulum: molecular cloning and comparison with higher plants and a bacterium

An almost complete cDNA clone [pPPI (AcVP gene), 3104 bp in length/open rea ding frame from 795 to 2960 bp/721 amino acids with a molecular weight of 7 4 406] encoding Acetabularia H+-translocating inorganic pyrophosphatase was isolated from total RNA using reverse-transcription and PCR techniques, Al ignments of the primary structure to that of similar enzmes in higher plant s and Rhodospirillum rubrum revealed that overall similarities were around 50%, the C-terminal half was well conserved but the N-terminal half showed divergencies except in a postulated substrate-binding domain. By Northern a nalysis, about 3.2 kb RNA mainly hybridized with 5'-untranslated region spe cific RNA probe of the AcVP gene.