Galectin from caprine brain: Subunit structure, carbohydrate specificity and its immunological relationship

A soluble β-galactoside binding lectin (galectin) was isolated from caprine brain by ammonium sulphate fractionation and affinity chromatography on lactosyl-Sepharose 4B column. The galectin with Mr 13800±400 on SDS-PAGE had gel filtration behaviour which was consistent with a molecular weight of 14.1 kDa, suggesting that the galectin is a monomeric protein. Amino acid composition indicated that the galectin was predominantly acidic in nature. The most potent saccharide inhibitors tested were lactose and p-nitrophenyl-β-D-galactopyranoside. The galectin preferentially binds to trypsinized human type A erythrocytes rather than O and B. Antibodies raised against the caprine brain galectin crossreacted with sheep and buffalo brain galectins showing the antigenic relationship between them.