InterPro domain: IPR001229

The jacalin-like mannose-binding lectin domain has a beta-prism fold consisting of three 4-stranded beta-sheets, with an internal pseudo 3-fold symmetry. Some proteins with this domain stimulate distinct T- and B- cell functions, such as the plant lectin jacalin, which binds to the T-antigen and acts as an agglutinin. The domain can occur in tandem-repeat arrangements with up to six copies, and in architectures combined with a variety of other functional domains. While the family was initially named after an abundant protein found in the jackfruit seed, taxonomic distribution is not restricted to plants. The domain is also found in the salt-stress induced protein from rice and an animal prostatic spermine-binding protein. Proteins containing this domain include:

• Jacalin, a tetrameric plant seed lectin and agglutinin from Artocarpus heterophyllus (jackfruit), which is specific for galactose [ 1 ].
• Artocarpin, a tetrameric plant seed lectin from A. heterophyllus [ 2 ].
• Lectin MPA, a tetrameric plant seed lectin and agglutinin from Maclura pomifera (Osage orange), [ 3 ].
• Heltuba lectin, a plant seed lectin and agglutinin from Helianthus tuberosus (Jerusalem artichoke) [ 4 ].
• Agglutinin from Calystegia sepium (Hedge bindweed) [ 5 ].
• Griffithsin, an anti-viral lectin from red algae (Griffithsia species) [ 6 ].

1. Crystal structure of the jacalin-T-antigen complex and a comparative study of lectin-T-antigen complexes. J. Mol. Biol. 321, 637-45
2. Structural basis for the carbohydrate specificities of artocarpin: variation in the length of a loop as a strategy for generating ligand specificity. J. Mol. Biol. 338, 757-70
3. Structure of the complex of Maclura pomifera agglutinin and the T-antigen disaccharide, Galbeta1,3GalNAc. J. Biol. Chem. 273, 6312-8
4. Helianthus tuberosus lectin reveals a widespread scaffold for mannose-binding lectins. Structure 7, 1473-82
5. The crystal structure of the Calystegia sepium agglutinin reveals a novel quaternary arrangement of lectin subunits with a beta-prism fold. J. Biol. Chem. 279, 527-33
6. Domain-swapped structure of the potent antiviral protein griffithsin and its mode of carbohydrate binding. Structure 14, 1127-35