Jacobs J W, Simpson E, Lennarz W J, Welply J K
Biochem Biophys Res Commun. 1985 Jul 16;130(1):343-9. doi: 10.1016/0006-291x(85)90423-1.
Tumor-derived, large molecular weight forms of calcitonin, have been postulated to result from glycosylation of the hormone. To address this question we have examined the glycosylation of calcitonin in vitro and in cultured thyroidal C-cells. We show that native, undenatured calcitonin is an active substrate for oligosaccharyltransferase and that glycosylation of calcitonin by the transferase is inhibited by tunicamycin. In addition, calcitonin is an effective competitive inhibitor of the glycosylation of a known peptide substrate for oligosaccharyltransferase. Pulse-labelling of cultured medullary thyroid carcinoma cells with [3H]-mannose indicate that detectable quantities of carbohydrate-containing forms of calcitonin are produced in these cells. These data indicate that glycosylation of calcitonin is one mechanism whereby tumor cells could produce higher molecular weight forms of the hormone.
肿瘤来源的大分子量降钙素形式，据推测是该激素糖基化的结果。为解决这一问题，我们在体外和培养的甲状腺C细胞中研究了降钙素的糖基化。我们发现天然的、未变性的降钙素是寡糖基转移酶的活性底物，并且衣霉素可抑制该转移酶对降钙素的糖基化作用。此外，降钙素是寡糖基转移酶已知肽底物糖基化的有效竞争性抑制剂。用[3H] - 甘露糖对培养的甲状腺髓样癌细胞进行脉冲标记表明，这些细胞中产生了可检测量的含碳水化合物形式的降钙素。这些数据表明，降钙素的糖基化是肿瘤细胞产生该激素更高分子量形式的一种机制。
