title: The 55-kDa polypeptide released from spinach thylakoid membranes with 1 M LiCl is not the beta subunit of chloroplast F1.
abstract: It was reported by Frasch et al. (Frasch, W. D., Green, J., Caguiat, J., and Mejia, A. (1989) J. Biol. Chem. 264, 5064-5069) that washing spinach thylakoid membranes with 1 M LiCl caused the release of the beta subunit of chloroplast F1 (CF1) which, existing as 180-kDa complexes of beta 3, retained considerable ATPase activity. We repeated their procedures and confirmed that a CF1 beta-like 55-kDa polypeptide was a major constituent of the 1 M LiCl-washed extract. However, the extract contained another polypeptide of which the Mr was 14,000, and these two polypeptides comprised a complex with approximate Mr 550,000 that had the same mobility in native polyacrylamide gel electrophoresis as that of ribulose-1,5-bisphosphate carboxylase. Only very low ATPase activity, less than 1% of the reported value, was detected for the extract and the purified complex. Antibody against the beta subunit of F1 from a thermophilic bacterium PS3 showed a clear cross-reactivity with the CF1 beta subunit but not with the 55-kDa polypeptide. Analysis of the N-terminal amino acid sequences of the 55- and 14-kDa polypeptides and the whole complex revealed that the complex was ribulose-1,5-bisphosphate carboxylase and that the 55- and 14-kDa polypeptides were its large and small subunits, respectively.
authors: Department of Life Science, Faculty of Science, Tokyo Institute of Technology, Yokohama, Japan.
authors: M H
authors: MH
authors: Sato
authors: T
authors: T
authors: Hisabori
authors: M
authors: M
authors: Yoshida
mesh_terms: D000595:Amino Acid Sequence; D002736:Chloroplasts / Q000032:analysis / Q000201:enzymology; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D007425:Intracellular Membranes / Q000032:analysis* / Q000201:enzymology; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000302:isolation & purification* / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010940:Plant Proteins / Q000302:isolation & purification*; D010944:Plants / Q000032:analysis / Q000201:enzymology; D006180:Proton-Translocating ATPases / Q000302:isolation & purification*; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics / Q000302:isolation & purification*; D012689:Sequence Homology, Nucleic Acid
chemical_list: D046911:Macromolecular Substances; D008565:Membrane Proteins; D010940:Plant Proteins; D006180:Proton-Translocating ATPases; D012273:Ribulose-Bisphosphate Carboxylase