Fig. 3.

PII inhibits chloroplastic ACCase activity. (A) ACCase activity was assayed in the absence (−PII) and presence of 0.36 μM PII (+PII). The specificity of PII inhibition was tested by addition of recombinant NAGK (1.51 μM) or CPO (1.35 μM) (plastidial proteins), or BSA (0.72 μM), a nonplant protein. (B) The response curve of ACCase activity to increasing concentrations of trimeric PII showed that the inhibition was PII-dose-dependent. The data represent the average value (±SE) from 5 (PII, NAGK, CPO, BSA) and 4 (PII-dose-dependence) experiments carried out on different chloroplast preparations.