Cicer arietinum lectin or agglutinin (CAL/CPA) is a homodimer composed of two subunits.This lectin is a glycoprotein that contains 4.5% neutral sugars and is basic in nature (pI: 9.0). It’s haemagglutination activity is inhibited by fetuin and desialylated fetuin with a carbohydrate specificity for fetuin and p-Nitrophenyl N-acetyl-α-D-galactoside. CAL possess complex-sugar specificity for N-glycans and N-acetyl-D-galactosamine, and elutes with acetyl-D-galactosamine. Although neither human or rabbit erythrocytes are agglutinated by this lectin, pronase-treated rabbit and human erythrocytes have been successfully agglutinated. None of the sugars, such as glucose, mannose or galactose, nor their derivatives, disaccharides, trisaccharides and tetrasaccharides have any effect on the agglutination of this lectin.
Colloidal gold can be used to visualize localization of specific saccharide moieties and examine the distribution of plasma membrane glycoproteins based on the binding pattern of Cicer arietinum Lectin (CAL/CPA). Colloidal gold labeled lectins can be viewed via electron microscopy.