Enhanced glycosylation of a melanoma cell surface glycoprotein by retinoic acid: carbohydrate chain analysis by lectin binding.
Retinoic acid (RA) inhibits the growth of mouse S91-C2 melanoma cells and enhances the glycosylation of a cell surface sialoglycoprotein (gp160). The present study analyzed the binding of 125I-labeled lectins to gp160 within polyacrylamide slab gels after electrophoretic separation of cellular macromolecules. Wheat germ agglutinin (WGA) and concanavalin A (Con A) bound to gp160 of RA-treated cells (RA-gp160) more extensively than to gp160 of control cells (C-gp160). Lens culinaris hemagglutinin (LCH), pokeweed mitogen (PWM), Ricinus communis agglutinin I (RCAI), and peanut agglutinin (PNA) failed to bind to either C-gp160 or to RA-gp160. The binding of WGA was greatly diminished after sialic acid removal. In contrast, desialylation made possible the binding of RCAI to RA-gp160. LCH, PWM and PNA did not bind to gp160 even after desialylation. Smith degradation exposed WGA-binding sites on RA-gp 160. These results suggest that gp 160 contains one or more highly branched, sialylated, N-linked complex-type side chains and lacks O-linked oligosaccharides and poly N-acetyllactosamine side chains.
Department of Tumor Biology, University of Texas M.D. Anderson Hospital and Tumor Institute at Houston 77030.
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D000818:Animals; D002240:Carbohydrate Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D043384:Glutamyl Aminopeptidase; D006031:Glycosylation; D007457:Iodine Radioisotopes; D037102:Lectins / Q000378:metabolism*; D008546:Melanoma, Experimental / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000378:metabolism*; D012795:Sialoglycoproteins / Q000378:metabolism*; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D007457:Iodine Radioisotopes; D037102:Lectins; D009363:Neoplasm Proteins; D012795:Sialoglycoproteins; D014212:Tretinoin; C054942:ENPEP protein, human; D043384:Glutamyl Aminopeptidase