Cell Surface Radiolabeling of the Carbohydrate Moieties of the Plasma Membrane Major Glycoprotein of AH-66 Hepatoma Ascites Cells

Abstract

The major plasma memebrane glycoproteins of AH-66 cells were radiolabeled by three methods which are known to label cell surface carbohydrates. The labeled components were separated by polyacrylamide gel electrophoresis and detected by fluorography. The AH-66 cells were found to be unusual because a single major glycoprotein with an apparent molecular weight of 165000 was almost exclusively labeled by both neuraminidase-galactose oxidase-NaB³H₄ and dilute periodate-NaB³H₄ treatments. The major glycoprotein was not labeled by galactose oxidase-NaB³H₄ treatment. When the major glycoprotein labeled by the neuraminidase-galactose oxidase-NaB³H₄ procedure was solubilized with Triton X-100 and then subjected to affinity chromatography on Sepharoseconjugated Ricinus communis agglutinin II, the ³H-labeled major glycoprotein bound to Sepharose-conjugated Ricinus communis agglutinin II lectin and was eluted with lactose. These results indicated that the major glycoprotein contained sialyl-galactosyl or sialyl-N-acetylgalactosaminyl terminal groups, which are exposed on the external surface of the plasma membranes of AH-66 cells.