Biochemical and immunocytochemical identification of conglutin gamma, a lupin seed lectin, in the roots of young germinating seedlings

Polyclonal antibodies directed against polypeptide epitopes of conglutin gamma, a glycosylated lectin in lupin seed, have been used to identify and quantify this protein in root extracts of germinating lupins. The highest conglutin gamma content was found in protein extracts of root elongation zones after 5 to 7 days germination. Root conglutin gamma showed the same subunit composition, glycosylation pattern, isoelectric point, and lectin activity as the cotyledonary one. Immunolocalization experiments on root thin sections demonstrated that conglutin gamma is chiefly present in the intercellular spaces of the cortical parenchyma, where it forms large aggregates. Labelling of the Golgi complexes and the area between the plasmalemma and cell wall revealed the conglutin gamma pathway from post-synthetic processing to excretion via the secretory system.