pyrophosphate and phenylbenzoquinone

It has been shown for the first time that several photosystem-II thylakoid proteins and the main chlorophyll-a/b light-harvesting complex can be phosphorylated with inorganic pyrophosphate as phosphate donor. With pyrophosphate, as with ATP, the protein-kinase reaction is dependent on light or a strong reducing agent. The reaction which can be demonstrated in well-washed spinach thylakoids is dependent on electron transport and is controlled by the redox state of the plastoquinone pool. It is suggested that the pyrophosphate-dependent thylakoid protein phosphorylation is mediated by the same kinase which is responsible for the ATP-dependent protein phosphorylation. This pyrophosphate-dependent kinase activity may be derived from an evolutionary precursor from which ATP-dependent protein phosphorylation also developed.

Topics: Adenosine Triphosphate; Benzoquinones; Diphosphates; Diuron; Electrophoresis, Polyacrylamide Gel; Light-Harvesting Protein Complexes; Membrane Proteins; Methylphenazonium Methosulfate; Phosphorylation; Photosynthetic Reaction Center Complex Proteins; Photosystem II Protein Complex; Plants; Protein Kinases; Proton-Translocating ATPases