Jacalin, or Artocarpus integrifolia lectin, is a tetrameric two-chain lectin with a molecular weight of 66 kDa. It is a α-D-galactose binding lectin purified from jack fruit (Artocarpus integrifolia) seeds.

Applications include isolating IgA from human serum and colostrums, isolating human plasma glycoproteins and histochemistry. It also binds IgD.