EFFECTS OF CALMODULIN AND CALMODULIN-BINDING PROTEIN BP-10 ON PHOSPHORYLATION OF THYLAKOID MEMBRANE-PROTEIN

Light-induced phosphorylation of endogenous thylakoid membrane protein can be inhibited markedly by a novel inhibitor CaMBP-10 which is disc overed and isolated from plant. The inhibitory effect of BP-10 can be eliminated by addition of CaM. At the same time, the phosphorylation c an also be inhibited by EGTA or CaM antagonists, such as TFP (trifluop erazine) and W-7 (N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide) . This result implies that (i) Ca2+ and CaM most likely participate in and regulate plant photosynthesis; (ii) the kinase that catalyzes thy lakoid membrane protein phosphorylation fan be regulated by Ca2+ and C aM. However, the further experiments indicate that BP-10 has no effect on dephosphorylation of thylakoid phosphoproteins.