Novotná Z., Linek J., Hynek R., Martinec J., Potocký M., Valentová O.: Plant PIP₂ dependent phospholipase D activity is regulated by phosphorylation. FEBS Letters 2003, 554, 50-54

Phospholipase D (PLD) forms the major family of phospholipases that was first discovered and cloned in plants. In this report we have shown, for the firs time, that C2 phosphatidylinositol-4,5-bisphosphate (PIP₂)-dependent PLD(s) from 5 day hypocotyls of Brassica oleracea associated with plasma membrane is covalently modified-phosphorylated. Pre-incubation of the plasma membrane fraction with acid phosphatase resulted in concentration-dependent inhibition of PIP₂-dependent PLD activity. Using matrix-assisted laser desorption/ionization time of Łight mass spectrometry of tryptic in-gel digests, the BoPLDg1;2 isoform was identified. Comparing the spectra of the proteins obtained from the plasma membrane fractions treated and non-treated with acid phosphatase, three peptides difering in the mass of the phosphate group (80 Da) were revealed: TMQMMYQTIYK, EVADGTVSVYNSPR and KASKSRGLGK which possess five potential Ser/Thr phosphorylation sites. Our findings suggest that a phosphorylation/dephosphorylation mechanism may be involved in the regulation of plant PIP₂-dependent PLDg activity.