Jacalin lectin (AIA) is isolated from jackfruit seeds (Artocarpus integrifolia). The lectin belongs to the family of galactose-binding lectins and has a tetrameric two-chain structure with a weight of 66 kDa. Lectins are, due to their specific binding to carbohydrate structures on the cell surface or elsewhere useful in haematology, immunology or as specific markers for membrane glycoprotein structures.

Jacalin is preferably used in applications to isolate IgA from human serum, isolating human plasma glycoproteins and for applications in histochemistry. The lectin is blood group non-specific after neuraminidase treatment and agglutinates human erythrocytes at a concentration of >7,8µg/mL. A post-translational proteolytic modification of Jacalin gives the lectin a novel carbohydrate-binding site involving the N terminus of the a-chain. The relative affinities of the lectin for galactose derivatives, as well as the structural basis of its T-antigen specificity, are explained by its protein structure.