Sano S, Okazaki K, Yamamoto Y, Slomiany A, Slomiany B L
First Department of Internal Medicine, Kochi Medical School, Japan.
J Gastroenterol. 1994 Dec;29(6):685-94. doi: 10.1007/BF02349272.
We studied the biosynthesis of mucin in the human stomach using an anti-mucin core peptide monoclonal antibody, 3G12. Human stomach mucosa was labeled with [35S]methionine, and chased for 3 h. An approximately 60-kDa subunit of human gastric mucin precursor protein was detected in the intracellular product. Under nonreducing conditions, dimer, trimer, and tetramer mucin precursor protein (120, 180, 240 kDa) were detected. Treatment with tunicamycin or endo-beta-N-acetylglucosaminidase H had no effect on the 60-kDa subunit and its oligomers. Extracellular products contained only the high molecular weight mucin, and the secretion was not affected by tunicamycin. By treatment with monensin or brefeldin A, the mature mucin was not secreted extracellularly. These findings suggested that a 60-kDa subunit of the mucin precursor protein was biosynthesized into mature mucin after oligomerization to tetramers, and that neither the oligomerization nor the intracellular transport of the mucin in the human stomach was associated with N-glycosylation.
我们使用抗粘蛋白核心肽单克隆抗体3G12研究了人胃中粘蛋白的生物合成。用人胃黏膜进行[35S]甲硫氨酸标记，并追踪3小时。在细胞内产物中检测到了人胃粘蛋白前体蛋白的一个约60 kDa的亚基。在非还原条件下，检测到了二聚体、三聚体和四聚体粘蛋白前体蛋白（120、180、240 kDa）。用衣霉素或内切β-N-乙酰葡糖胺酶H处理对60 kDa亚基及其寡聚体没有影响。细胞外产物仅含有高分子量粘蛋白，且分泌不受衣霉素影响。通过用莫能菌素或布雷菲德菌素A处理，成熟粘蛋白未分泌到细胞外。这些发现表明，粘蛋白前体蛋白的一个60 kDa亚基在寡聚化为四聚体后被生物合成成熟粘蛋白，并且人胃中粘蛋白的寡聚化和细胞内转运均与N-糖基化无关。
