Figure 2.

Synthesis of PIP₂ and the specific activity of PIP 5-kinase changed during gravistimulation. Plasma membranes were prepared from upper and lower halves of pulvinus tissue at the indicated times of gravistimulation and were assayed in vitro for PIP₂ formation from endogenous (A) or exogenous (B) substrate. Data are from one representative experiment where plants were stimulated and harvested in the dark. Similar fluctuations were obtained when plants were stimulated and harvested in the light. Dotted line, upper half of pulvinus; solid line, lower half of pulvinus. Each data point represents the average from duplicate values.