Schwaiger H, Tanner W
Eur J Biochem. 1979 Dec 17;102(2):375-81. doi: 10.1111/j.1432-1033.1979.tb04252.x.
A crude membrane fraction was prepared from isolated aleurone layers, the secretory tissue of barley grains. The layers were pre-incubated in the presence or absence of the phytohormone gibberellic acid. The membranes catalyzed the transfer of [14C]mannose from GDP-[14C]mannose and of N-[14C]acetylglucosamine from UDP-N-[14C]acetylglucosamine to endogenous and exogenous dolichyl monophosphate. When gibberellic acid was present during the pretreatment the activity of the transferases was increased by a factor of two to three. A significantly increased activity was observable within four hours after the addition of gibberellic acid, whereas the gibberellic-acid-induced secretion of the glycoprotein alpha-amylase started only after 12 h. Tunicamycin inhibited the secretion of alpha-amylase by 60 to 80%. Intracellularly, however, no alpha-amylase was found to accumulate. On the other hand, tunicamycin did not inhibit the rate of total protein synthesis by more than 10%. The possibility is discussed that the synthesis of the protein portion of glycoproteins is specifically inhibited, when glycosylation is prevented.
从大麦籽粒的分泌组织糊粉层中制备了粗膜组分。将糊粉层在有或没有植物激素赤霉素的情况下进行预孵育。这些膜催化了GDP-[14C]甘露糖中的[14C]甘露糖以及UDP-N-[14C]乙酰葡糖胺中的N-[14C]乙酰葡糖胺向内源和外源二磷酸多萜醇的转移。当预处理过程中存在赤霉素时，转移酶的活性提高了两到三倍。添加赤霉素后4小时内可观察到活性显著增加，而赤霉素诱导的糖蛋白α-淀粉酶的分泌仅在12小时后开始。衣霉素抑制α-淀粉酶的分泌达60%至80%。然而，在细胞内未发现α-淀粉酶积累。另一方面，衣霉素对总蛋白质合成速率的抑制不超过10%。文中讨论了在糖基化被阻止时，糖蛋白蛋白质部分的合成是否会受到特异性抑制的可能性。
