Plant Secretomes: Current status and future perspectives

Plant secreted proteins have biological functions which are important in the formation of cell walls, cellular communication, and defense against pathogens. We analyzed 1704 secreted proteins from a total of 22513 plant proteins, all of which were manually curated and annotated in the UniProt database. Of the secreted plant proteins analyzed, 55% and 13% are curated from Arabidopsis thaliana and rice, respectively. Gene ontology cellular components analysis revealed that 84% of them are located in the extracellular region, cell wall, or extracellular space. Molecular functional domain analysis showed that 33% had hydrolase activity and 29% had binding activity. Signal peptide analysis revealed that 97.5% of secreted proteins had signal peptides. The information is anticipated to be used to computationally identify more secreted proteins in plants and to construct a plant secretome knowledge database.