Rice plastidial N-glycosylated nucleotide pyrophosphatase/phosphodiesterase is transported from the ER-golgi to the chloroplast through the secretory pathway.
A cDNA encoding previously purified and characterized diphosphonucleotide phosphatase/phosphodiesterase (PPD1) from yellow lupin (Lupinus luteus L.) was identified. The ppd1 gene encodes a protein containing a cleavable signal sequence. A functional expression of PPD1 in Saccharomyces cerevisiae confirmed the proper gene identification. A gene homologous to ppd1, encoding a putative membrane protein (PPD2), as well as fragments of two other genes encoding PPD3 and PPD4 proteins were also isolated. Amino acids composing the putative active center of PPD1 and PPD2 are similar to those present in known purple acid phosphatases, which suggests that the reported genes might encode a novel group of specific metallophosphatases. RT-PCR revealed that the corresponding PPD1 mRNA accumulates in stems and leaves, and PPD2 mRNA in stems, leaves and seedlings.