D-mannose/D-glucose-binding lectin. Homotetramer. Seed. The beta and gamma chains are produced by partial proteolytic processing of the lectin alpha chain by an asparaginyl endopeptidase. Mixture of 60% alpha lectin and 40% of its beta and gamma proteolytic fragments. Binds one manganese (or another transition metal) ion and one calcium ion. The metal ions are essential for the saccharide-binding and cell-agglutinating activities. Belongs to the leguminous lectin family.