The effect of cycloheximide on the glycosylation of lactating-rabbit mammary glycoproteins.
1. Cycloheximide inhibited immediately the incorporation of L-[4,5-3H]leucine and D-]2-3H]mannose into mammary proteins, suggesting that the mannosylation of mammary glycoproteins requires the continued supply of newly synthesized polypeptides. 2. The incorporation of radioactivity from N-acetyl-D-[1-14C] glucosamine into protein was not inhibited until approx. 30 min after cycloheximide addition. Much (greater than 90%) of this radioactivity was present as N-acetylgalactosamine. 3. N-Glycosylation appears to be inhibited immediately by cycloheximide due to a lack of newly synthesized acceptor polypeptides, whereas O-glycosylation continues for 30 min, the time taken for acceptor peptides to move from their site of synthesis to the Golgi region and for completion of glycosylation. 4. There was a transient increase in the incorporation of mannose into lipid-linked oligosaccharide in the presence of cycloheximide, followed by a decrease in the radioactivity in this fraction. 5. The major lipid-linked oligosaccharide extracted from explants incubated for 2h in the presence of cycloheximide (6-7 monosaccharide units) was smaller than that extracted from control explants (10-12 monosaccharide units).
D000818:Animals; D003513:Cycloheximide / Q000494:pharmacology*; D005260:Female; D005944:Glucosamine / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism*; D066298:In Vitro Techniques; D007774:Lactation; D007930:Leucine / Q000378:metabolism; D050356:Lipid Metabolism; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000378:metabolism*; D008358:Mannose / Q000378:metabolism; D011247:Pregnancy; D011817:Rabbits
D006023:Glycoproteins; D003513:Cycloheximide; D007930:Leucine; D005944:Glucosamine; D008358:Mannose