Isolation of a 220-kilodalton protein with lectin properties from a virulent strain of Entamoeba histolytica.

A 220-kilodalton (kDa) protein with lectin properties was isolated from Entamoeba histolytica strain HM1:IMSS and was purified by Sepharose 4B chromatography and electroelution from 5% SDS-polyacrylamide gels. The protein contains 9% carbohydrate by weight; is rich in hydrophobic residues; and is very immunogenic in mice, hamsters, and rabbits. The protein binds to fixed monolayers of MDCK cells and inhibits trophozoite attachment to the cultured cells. The 220-kDa protein agglutinates human erythrocytes, and agglutination is inhibited by micromolar concentrations of hyaluronic acid, chitin, chitin-derived products (chitotriose), and antibodies to the purified protein. The 220-kDa protein is recognized by an antibody to the membrane but not by antibodies to other subcellular fractions. We therefore suggest that this 220-kDa protein with lectin properties is a component of the plasma membrane and could be one of the putative "receptor" molecules involved in cell and/or matrix attachment.