title: Evidence for the existence of a thylakoid intrinsic protein that binds ferredoxin-NADP+ oxidoreductase.
abstract: The ferredoxin-NADP+ oxidoreductase of spinach chloroplasts was purified from a Triton X-100 thylakoid extract closely associated with an intrinsic polypeptide of 17.5 kDa. The 17.5-kDa polypeptide-reductase complex differs from soluble ferredoxin-NADP+ reductase in (a) its elution profile in an Affi-Gel blue column; (b) its behavior in isoelectric focusing electrophoresis; and (c) giving different immunoelectrophoretic arcs. The diaphorase activity of the purified complex showed the same pH profile of thylakoid-bound reductase. The curve changed to a form similar to that of soluble reductase after dissociation of the complex. Dissociation allowed separation of the components and was reversible. It is suggested that the 17.5-kDa intrinsic polypeptide is the reductase-binding protein and that it may play an important role in the physiological regulation of the reductase and of photosynthetic electron transport.
mesh_terms: D060365:Chloroplast Proteins; D004591:Electrophoresis, Polyacrylamide Gel; D005287:Ferredoxin-NADP Reductase / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000378:metabolism*; D008970:Molecular Weight; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D010940:Plant Proteins; D010944:Plants / Q000378:metabolism*
chemical_list: D060365:Chloroplast Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D010940:Plant Proteins; D005287:Ferredoxin-NADP Reductase; D009247:NADH, NADPH Oxidoreductases