THE S-TYPE LECTIN FROM CALF HEART-TISSUE BINDS SELECTIVELY TO THE CARBOHYDRATE CHAINS OF LAMININ

We report that the S-type lectin in calf heart tissue, termed calf heart agglutinin (CHA), binds to immobilized mouse laminin in ligand blotting and solid-phase radioligand binding assays. When compared with other glycoproteins, radioiodinated CHA binds preferentially to immobilized laminin. The binding is saturable with a Kd of 9.2 × 10-7 m and is competitively inhibited by nonradiolabeled CHA as well as a similar lectin from porcine heart tissue. Both lactose and N-acetyllactosamine are good inhibitors of binding to laminin but binding is not inhibited by heparin. Exoglycosidase treatments demonstrated that the binding of radioiodinated CHA to laminin is not dependent on terminal sialyl-, fucosyl-, β- or α-linked galactosyl residues, whereas treatment of laminin with endo-β-galactosidase significantly decreases the lectin binding. Thus, CHA binds selectively to the poly-N-acetyllactosamine chains on complex-type Asn-linked oligosaccharides in laminin. © 1990.