Abstract
Protein phosphorylation in isolated, intact pea chloroplasts was measured during the onset of CO2‐dependent O2evolution. Total incorporation of32P (from32Pi) into the light‐harvesting chlorophylla/b—protein was found to be less sensitive than O2evolution to inhibition by the uncouplers FCCP and NH4C1 It is concluded that changes in the rate of ATP synthesis cannot affect protein phosphorylation without also affecting the rate of CO2‐fixation in this system. The ATP/ADP ratio is therefore unlikely to regulate photosynthetic protein phosphorylation under normal physiology conditions.