Oligomycin-insensitive incorporation of 32P into chloroplast protein by illumination

³²P incorporation into the protein fraction of chloroplast fragmentsby short illumination was investigated under various phosphorylatingconditions. ³²P incorporation was generally accompanied by cyclic and non-cyclicphotophosphorylations and also by formation of a high energyintermediate "X_E". However, the addition of a DPIP-ascorbatecouple caused inhibition of ³²P incorporation, while ATP formationproceeded. Effects of inhibitors and uncouplers of photophosphorylationon the formation of protein-bound ³²P were generally similarto those on ATP formation. AT³²P was not utilized for protein-bound ³²P formation in thedark by chloroplast fragments, but its radioactivity was transferredinto the chloroplast protein fraction in the light. Oligomycininhibited ATP formation but did not inhibit protein-bound ³²Pformation. m-Cl-CCP blocked both reactions. This suggests thatprotein-bound ³²P is not an actual intermediate in the phosphorylativeprocess leading to formation of ATP. It is probably formed ona side pathway from an intermediate of ATP formation. Analyses of protein-bound ³²P after digestion with proteaseand lipase showed that the ³²P incorporated was bound to peptidesin chloroplast lamellae. The possible form of this bound ³²Pis discussed. (Received November 22, 1971; )