Effects of 20-hydroxyecdysone and tunicamycin on glycoprotein synthesis in an insect cell line

Treatment of CH-MRRL cells with either 20-hydroxyecdysone or tunicamycin resulted in a decrease in the incorporation of labeled sugars into glycoproteins. This change appears to be largely quantitative, as few qualitative changes in protein bands were apparent as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Tunicamycin caused a greater change in the amount of labeled sugar incorporated into specific glycoproteins than did 20-hydroxyecdysone. This was more apparent in ( super(14)C)-mannose-labeled than in( super(14)C)-N-acetylglycosamine-labeled glycoproteins. Both compounds caused changes in cell surface glycoproteins. These changes are discussed in relation to previous work on binding of lectins to the cell surface and on the mode of action of tunicamycin.