title: Extracellular sunflower proteins: evidence on non-classical secretion of a jacalin-related lectin.
abstract: Extracellular proteins from sunflower seedlings were analyzed by electrophoresis followed by peptide mass fingerprinting. Tentative identification revealed novel proteins for this crop. A significant number of those proteins were not expected to be extracellular because they lacked the typical signal peptide responsible for secretion. In silico analysis showed that some members of this group presented the characteristic disordered structures of certain non-classical and leaderless mammalian secretory proteins. Among these proteins, a putative jacalin-related lectin (Helja) with a mannose binding domain was further isolated from extracellular fluids by mannose-affinity chromatography, thus validating its identification. Besides, immunolocalization assays confirmed its extracellular location. These results showed that a lectin, not predicted to be secreted in strict requirement of the N-terminal signal peptide, occurs in a sunflower extracellular compartment. The implications of this finding are discussed.
authors.affiliation: Instituto de Investigaciones Biologicas, Universidad Nacional de Mar del Plata-CONICET, Funes 3250, 7600 Mar del Plata, Argentina.
authors.forename: Marcela
authors.initials: M
authors.lastname: Pinedo
authors.forename: Mariana
authors.initials: M
authors.lastname: Regente
authors.forename: Mercedes
authors.initials: M
authors.lastname: Elizalde
authors.forename: Ivana Y
authors.initials: IY
authors.lastname: Quiroga
authors.forename: Luciana A
authors.initials: LA
authors.lastname: Pagnussat
authors.forename: Jesus
authors.initials: J
authors.lastname: Jorrin-Novo
authors.forename: Ana
authors.initials: A
authors.lastname: Maldonado
authors.forename: Laura
authors.initials: L
authors.lastname: de la Canal
mesh_terms: D000595:Amino Acid Sequence; D045604:Extracellular Fluid / Q000378:metabolism*; D006368:Helianthus / Q000166:cytology* / Q000378:metabolism*; D008969:Molecular Sequence Data; D037121:Plant Lectins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D021382:Protein Sorting Signals; D021381:Protein Transport; D040901:Proteomics; D015203:Reproducibility of Results
chemical_list: D037121:Plant Lectins; D021382:Protein Sorting Signals; C043696:jacalin