Multiple phosphorylation sites in the beta subunit of thylakoid ATP synthase.
Proteomic analyses of the beta subunit of the plastid ATP synthase of barley (Hordeum vulgare L.) revealed that mature protein was not carboxy terminus processed and suggested the correction of the 274 codon (GAT to AAT) in the data bank that was confirmed by DNA sequencing. Six isoforms of the ATP synthase beta subunit with pI ranging from 4.95 to 5.14 were resolved by two-dimensional electrophoresis (2-DE). Mass spectrometry analyses indicated that the six isoforms differ in their phosphorylation degree, which was confirmed by the disappearance of more acidic forms after incubation with the protein phosphatase calcineurin. Six Ser and/or Thr were detected as phosphorylated, among them the conserved Thr-179 that is also phosphorylated in the beta subunit of human mitochondria. The results are discussed in relation with the proposed regulation of the ATP synthase by phosphorylation and 14-3-3 proteins.
del Riego
Guillermo
G
Departamento de Biología Vegetal, Universidad de Alcalá, Alcalá de Henares, Madrid 28871, Spain.
Casano
Leonardo M
LM
Martín
Mercedes
M
Sabater
Bartolomé
B
D000595:Amino Acid Sequence; D001665:Binding Sites; D025222:Chloroplast Proton-Translocating ATPases / Q000737:chemistry* / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D001467:Hordeum / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011487:Protein Conformation; D020033:Protein Isoforms; D021122:Protein Subunits; D020524:Thylakoids / Q000201:enzymology*
D020033:Protein Isoforms; D021122:Protein Subunits; D025222:Chloroplast Proton-Translocating ATPases