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Complementary immunolocalization patterns of cell wall hydroxyproline-rich glycoproteins studied with the use of antibodies directed against different carbohydrate epitopes.
Swords, K M; Staehelin, L A.
Afiliação
  • Swords KM; Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder 80309-0347.
Plant Physiol ; 102(3): 891-901, 1993 Jul.
Article em En | MEDLINE | ID: mdl-7506427
Antisera raised against the major hydroxyproline-rich glycoprotein (HRGP) in carrot (Daucus carota L.) taproot, extensin-1, and a minor HRGP, extensin-2, were characterized by western blot analysis, enzyme-linked immunosorbent assay, and periodate oxidation and found to be directed against carbohydrate epitopes shared by both glycoproteins. The anti-extensin-1 antibodies (gE1) target periodate-sensitive epitopes and may recognize the terminal alpha-1,3-arabinoside of extensin-1. The anti-extensin-2 antibodies (gE2) recognize periodate-insensitive epitopes, possibly binding the reducing, internal beta-1,2-arabinosides on the carbohydrate side chains. Despite the cross-reactivity of these antibodies, immunolocalization studies of carrot taproot and green bean (Phaseolus vulgaris L.) leaf tissues reveal a spatial segregation of gE1- and gE2-labeling patterns. The gE1 antibodies bind only to the cellulose-rich region of the cell wall (J.P. Staehelin and L.A. Stafstrom [1988] Planta 174: 321-332), whereas gE2 labeling is restricted to the expanded middle lamella at three cell junctions. Periodate oxidation of nonosmicated, thin-sectioned tissue abolishes gE1 labeling but leads to labeling of the entire cell wall by gE2, presumably as a result of unmasking cryptic epitopes on extensin-1 in the cellulose layer. Purified extensin-2 protein is more efficient than extensin-1 protein at agglutinating avirulent Pseudomonas strains lacking extracellular polysaccharide. Our results indicate that extensin-2 does not form a heterologous HRGP network with extensin-1 and that, in contrast to extensin-1, which appears to serve a structural role, extensin-2 could participate in passive defense responses against phytopathogenic bacteria.
Assuntos

Texto completo: 1 Base de dados: MEDLINE Métodos Terapêuticos e Terapias MTCI: Terapias_biologicas Assunto principal: Proteínas de Plantas / Plantas Medicinais / Verduras / Glicoproteínas / Fabaceae / Epitopos Idioma: En Revista: Plant Physiol Ano de publicação: 1993 Tipo de documento: Article

Texto completo: 1 Base de dados: MEDLINE Métodos Terapêuticos e Terapias MTCI: Terapias_biologicas Assunto principal: Proteínas de Plantas / Plantas Medicinais / Verduras / Glicoproteínas / Fabaceae / Epitopos Idioma: En Revista: Plant Physiol Ano de publicação: 1993 Tipo de documento: Article