title: Novel subsets of the Arabidopsis plasmalemma phosphoproteome identify phosphorylation sites in secondary active transporters.
abstract: The generation of novel subsets of phosphorylation sites is needed to complement the present Arabidopsis plasma membrane phosphoprotein repertoire, where several families of proteins are under-represented. In this work, different combinations of chromatographic steps were first compared for capacity to resolve model phosphopeptides before characterisation from PSD fragments in MALDI MS/MS. Nearly half of the phosphorylation sites detected in the Arabidopsis plasmalemma using the optimised procedure were novel, and two-thirds of protein accessions identified secondary active transporters. These included phosphate/H(+) symporters, ammonium and nitrate transporters, different alkali cation exchangers, a urea/H(+) symporter, a glucose transporter, a purine permease, and peptide transporters. There has been previous functional evidence for phosphorylation of only a minority of these, the regulation of others having been essentially investigated at the transcriptional level. The demonstration of active phosphorylation sites in such a diverse set of secondary transporter families suggests that this regulation level plays a major role in the response of plants to nutrient availability.
authors.affiliation: Laboratoire de Protéomique Fonctionnelle, UR1199, INRA, F-34060 Montpellier, France. hem@supagro.inra.fr
authors.forename: Sonia
authors.initials: S
authors.lastname: Hem
authors.forename: Valérie
authors.initials: V
authors.lastname: Rofidal
authors.forename: Nicolas
authors.initials: N
authors.lastname: Sommerer
authors.forename: Michel
authors.initials: M
authors.lastname: Rossignol
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism*; D001665:Binding Sites; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D010750:Phosphoproteins / Q000737:chemistry* / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D020543:Proteome / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D010750:Phosphoproteins; D020543:Proteome