title: Characterization of chloroplast thylakoid polypeptides in the 32-kDa region: polypeptide extraction and protein phosphorylation affect binding of photosystem II-directed herbicides.
abstract: In order to distinguish between two photosystem II proteins with apparent molecular weights of about 32 kDa, mild extraction procedures were used to remove several thylakoid membrane components. A 32-kDa protein that stained intensely with Coomassie brilliant blue could be extracted from the thylakoid membranes without removing the 32-kDa herbicide receptor protein, which stained poorly with Coomassie brilliant blue. The nonextracted protein was readily detectable after in vivo polypeptide labeling with [35S]methionine or after in vitro covalent tagging with [14C]azidoatrazine. The procedures used to extract the intensely stained, 32-kDa polypeptide resulted in changes in herbicide-binding characteristics, presumably due to conformational changes in the herbicide-binding environment. Alterations of membrane surface charge by protein phosphorylation also influenced herbicide binding.
mesh_terms: D002736:Chloroplasts / Q000378:metabolism*; D007887:Fabaceae / Q000378:metabolism; D006540:Herbicides / Q000378:metabolism*; D008970:Molecular Weight; D010455:Peptides / Q000378:metabolism*; D010766:Phosphorylation; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins / Q000378:metabolism*; D010946:Plants, Medicinal; D011485:Protein Binding; D011487:Protein Conformation
chemical_list: D006540:Herbicides; D010455:Peptides; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins