A galactose-specific and a mannose-specific lectin of the family of the jacalin-related lectins have been localized by immunofluorescence microscopy. The present localization studies provide for the first time unambiguous evidence for the cytoplasmic location of the mannose-specific jacalin-related lectin from rhizomes of Calystegia sepium, which definitely differs from the vacuolar location of the galactose-specific jacalin from Artocarpus integrifolia. These observations support the hypothesis that the galactose-specific jacalin-related lectins evolved from their mannose-specific homologues through the acquisition of vacuolar targeting sequences.
