A beta-D-galactoside binding protein from electric organ tissue of Electrophorus electricus

Abstract

Extracts of electric organ tissue of Electrophorus electricus contain a saccharide-binding protein, named electrolectin, which agglutinates trypsin-treated rabbit erythrocytes and is specifically inhibited by disaccharides containing nonreducing terminal beta-D-galactosyl residues. Electrolectin seems at least partially membrane-bound but is also found in soluble fractions of homoge-nates from which it can be purfied by affinity chromatography on cross-linked and desulfated agarose (ECD-Sepharose) as a protein of molecular weight 33,000. About 400 mg of electrolectin are present per kg of tissue. It has an affinity for lactose of 1.0 mM-1 and 5.5mM-1 as estimated, respectively, by hapten inhibition and fluorescence spectroscopy. Studies on the distribution of beta-D-galactoside-binding activity in animal tissues reveal particularly high levels in sheletal muscle tissue and in cultures of embryonic skeletal muscle and neuroblastoma cells.