Membrane Receptors of Mouse Lymphocytes for Various Lectins1

Abstract

The major glycoproteins which bind various lectins (Bauhinia purpurea, Lens culinaris, Pisum sativum, Ricinus communis, and wheat germ hemagglutinins) were isolated from splenic lymphocytes of DD-mice. The surface of the cells was radioiodinated using the enzyme lactoperoxidase and the crude membranes (microsomal fraction) were isolated from the radioiodinated cells. These membranes were solubilized with Triton X-100 and subjected to affinity chromatography on affinity adsorbents prepared by coupling the lectins to activated Sepharose 4B. The glycoproteins specifically eluted with haptenic sugars from the affinity adsorbents were analyzed according to their mobility on polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The mitogenic lectins (P. sativum, L. culinaris) and R. communis hemagglutinin, which preferentially interact with the sugar chains of the type found in serum glycoproteins (serum glycoprotein-type sugar chains), bind strongly membrane glycoproteins with molecular weights ranging from 80,000 to 20,000, whereas the other lectins, which can interact with sugar chains such as those of mucins (mucin-type sugar chains), bind membrane glycoproteins with molecular weights higher than 100,000. To characterize the receptor sites for mitogenic lectins on the surface of lymphocytes, the membrane glycoproteins of C3H/He-mouse splenic lymphocytes, which were specifically eluted from a column of P. sativum-Sepharose 4B, were further identified by immunoprecipitation with specific antisera. Immunoglobulins, possibly immunoglobulins M and D, and the histocompatibility-2-complex proteins (H-2D, H-2K, and Ia antigens) were found to be major receptor sites.