Diacylglycerol kinase in plasma membranes from wheat

AtDGK2, a Novel Diacylglycerol Kinase from Arabidopsis thaliana, Phosphorylates 1-Stearoyl-2-arachidonoyl-sn-glycerol and 1,2-Dioleoyl-sn-glycerol and Exhibits Cold-inducible Gene Expression

“…AtDGK2 activity was not significantly affected by CaCl 2 in the concentration range of 1-1000 M under our assay conditions, indicating that AtDGK2 may not be regulated by cytoplasmic Ca 2ϩ in vivo. Similar results were reported for tobacco and wheat DGKs (37,53). Sodium chloride (up to 0.8 M) has been reported to inhibit DGK activity in Rattus norvegicus (54).…”

“…To further confirm that the formation of PA was a result of AtDGK2 activity, the reaction mix was preincubated with the DGK inhibitor R59022, which has been shown to be active in both animal and plant cells (18,37,40,41). In our experiments, the decrease in PA formation was dependent on the concentration of the inhibitor (Fig.…”

“…The K m of 125 M for 1,2-DOG is rather low and indicates the high affinity of the enzyme for the substrate; for other DGK enzymes, K m values of up to 1 mM were reported (35,36). Regarding the specific activity, values of 3-20 pmol PA min Ϫ1 g of protein Ϫ1 were previously reported in biochemical studies for wheat (37) and tomato (17) DGK isoforms, both being significantly higher than the specific activity observed here for Arabidopsis AtDGK2. A specific activity of 0.4 pmol of PA min Ϫ1 g of protein Ϫ1 has been reported for the human DGK isoform (38), whereas another human DGK isoform, DGK␣, showed values higher than 20 pmol of PA min Ϫ1 g of protein Ϫ1 (39).…”

Rapid turnover of polyphosphoinositides in carnation flower petals

“…In addition, several enzymes involved in their metabolism, such as PtdIns kinase, PtdInsP kinase, DAG kinase, phospholipase C, and PtdInsP 2 monoesterase have been reported (Sandelius and Sommarin 1986;Heim and Wagner 1987;Pfaffmann et al 1987;McMurray and Irvine 1988;Sommarin and Sandelius 1988;Einspahr et al 1989;Tate et al 1989;Sandelius and Sommarin 1990;Kamada and Muto 1991;Lundberg and Sommarin 1992;Wissing et al 1989). While the basic elements of phosphoinositide metabolism have been shown to be present, relatively little is known about its turnover.…”

Phosphatidate Kinase, A Novel Enzyme in Phospholipid Metabolism (Characterization of the Enzyme from Suspension-Cultured Catharanthus roseus Cells)

“…The former proteins were also reported to partition in the surfactant-enriched phase after extraction with Triton X-114 (Bordier, 1981;Ganong and Delmore, 1991). When this method was applied to the present plasma membranes, PA kinase and DG kinase, which are also integral proteins of the plasma membrane (Lundberg and Sommarin, 1992;, were extracted efficiently by Triton X-114 and both plant lipid kinases were strongly enriched in the surfactant-enriched phase, whereas most of the extracted protein was found in the surfactantdepleted phase. These data indicate that PA kinase is an intrinsic membrane protein, as was found for DG kinase.…”