Abstract
There are at least five types of peroxisomes in higher plants (glyoxysomes, leaf peroxisomes, cotyledonary peroxisomes, root peroxisomes and unspecialized peroxisomes). A functional transition from glyoxysomes to leaf peroxisomes occurs during the postgerminative growth of seedlings. Glyoxysomes contain enzymes for fatty acid β-oxidation and the glyoxylate cycle that are involved in lipid metabolism. Leaf peroxisomes contain enzymes for photorespiratory glycolate metabolism. Protein phosphorylation is known to be involved in the regulation of many other pathways in plants. From peroxisomal proteomic analysis of etiolated Arabidopsis cotyledons, we identified the first protein kinase, GPK1, in glyoxysomes. However, the actual number of protein kinases and the general properties of protein phosphorylation in the peroxisome are still unknown. To investigate role of phosphorylation in metabolisms and functions of peroxisomes, we systemically identified protein kinases and phosphorylated proteins in peroxisomes.
