title: Proteomic analysis of leaf peroxisomal proteins in greening cotyledons of Arabidopsis thaliana.
abstract: Leaf peroxisomes are present in greening cotyledons and contain enzymes of the glycolate pathway that functions in photorespiration. However, only a few leaf peroxisomal proteins, that is hydroxypyruvate reductase (HPR), glycolate oxidase (GO) and alanine:glyoxylate aminotransferase 1 (AGT1), have been characterized, and other functions in leaf peroxisomes have not been solved. To better understand the functions of leaf peroxisomes, we established a method to isolate leaf peroxisomes of greening cotyledons. We analyzed 53 proteins by MALDI-TOF MS and then identified 29 proteins. Among them, five proteins are related to the glycolate pathway, four proteins function in scavenging of hydrogen peroxide and additionally 20 novel leaf peroxisomal proteins were identified. In particular, protein kinases and protein phosphatase were first identified as peroxisomal proteins suggesting that protein phosphorylation is one of the regulatory mechanisms in leaf peroxisomes. Novel leaf peroxisomal proteins contained five PTS1-like proteins that have sequences where one amino acid is substituted with another one in PTS1 sequences. The PTS1 motif was suggested to have novel PTS1 sequences.
authors.affiliation: Department of Cell Biology, National Institute for Basic Biology, Okazaki, 444-8585 Japan.
authors.forename: Youichiro
authors.initials: Y
authors.lastname: Fukao
authors.forename: Makoto
authors.initials: M
authors.lastname: Hayashi
authors.forename: Mikio
authors.initials: M
authors.lastname: Nishimura
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D018548:Cotyledon / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D006016:Glycolates / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000378:metabolism; D000074435:Peroxisome-Targeting Signal 1 Receptor; D020675:Peroxisomes / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation; D010860:Pigments, Biological / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000302:isolation & purification / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism; D020543:Proteome / Q000302:isolation & purification / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism
chemical_list: D006016:Glycolates; D008565:Membrane Proteins; D000074435:Peroxisome-Targeting Signal 1 Receptor; D010860:Pigments, Biological; D010940:Plant Proteins; D020543:Proteome; D018160:Receptors, Cytoplasmic and Nuclear; C031149:glycolic acid; D006861:Hydrogen Peroxide; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases