Intestinal epithelial cell differentiation-related changes in glycosyltransferase activities in rats.
Intestinal epithelial cell differentiation-related changes in glycosyltransferase activities in rats.
复制标题
大鼠肠上皮细胞分化相关的糖基转移酶活性变化。
DOI：
10.1016/0304-4165(84)90259-9
复制
发表时间：
1984
期刊：
影响因子：
--
通讯作者：
Weiser,MM
中科院分区：
文献类型：
--
作者：
Wilson,JR;Dworaczyk,DA;Weiser,MM
肠上皮细胞从隐窝迁移到绒毛尖端时会分化。制备来自大鼠小肠的上皮细胞的十级分隐窝至绒毛梯度，并测定匀浆中参与天冬酰胺连接寡糖延伸的三种糖基转移酶。 N-乙酰葡糖胺基转移酶 I 和 II（分别将 N-乙酰葡糖胺连接到 3' 或 6' 核心甘露糖的酶）用结构确定的糖肽作为特异性受体进行测定，半乳糖基转移酶用去唾液酸、半乳糖基胎球蛋白（半乳糖连接到暴露的 N-乙酰葡糖胺末端）进行测定。测定中包括糖苷酶和焦磷酸酶的抑制剂，以尽量减少底物或产物分解的影响。结果表明N-乙酰葡糖胺基转移酶I显示出从绒毛尖端的低点到隐窝下部区域的峰值增加的活性梯度。相反，N-乙酰氨基葡萄糖转移酶II显示出两个活性峰，一个在绒毛区，另一个在上隐窝区。半乳糖基转移酶活性也定义了一个与 N-乙酰氨基葡萄糖转移酶 I 观察到的梯度非常相似的梯度，其比活性在隐窝细胞中最高。三种酶的比活性水平与其作用的表观顺序相关：N-乙酰葡糖胺基转移酶 I ⪡N-乙酰葡糖胺基转移酶 II ⪡ 半乳糖基转移酶。这些结果表明，糖基转移酶的发育调节参与肠细胞分化过程中糖蛋白寡糖链的延长。
Intestinal epithelial cells differentiate as they migrate from the crypt-to-villus tip. A ten-fraction crypt-to-villus gradient of epithelial cells from rat small intestine was prepared and homogenates assayed for three glycosyltransferases involved in elongation of asparagine-linked oligosaccharides. TheN-acetylglucosaminyltransferases I and II (enzymes which attachN-acetylglucosamine to either the 3′ or 6′ core mannose, respectively) were assayed with structurally-defined glycopeptides as specific acceptors and galactosyltransferase was assayed with asialo, agalactosylfetuin (galactose is attached to exposedN-acetylglucosamine termini). Inhibitors of glycosidases and pyrophosphatases were included in the assays to minimize effects of breakdown of substrate or product. The results indicate theN-acetylglucosaminyltransferase I shows a gradient of activity increasing from a low at the villus tip to a peak in the lower crypt region. In contrast,N-acetylglucosaminyltransferase II showed two peaks of activity, one in the villus zone and another in the upper crypt region. Galactosyltransferase activity also defined a gradient quite similar to that observed forN-acetylglucosaminyltransferase I, its specific activity being highest in the crypt cells. The specific activity levels of the three enzymes correlated with the apparent order of their action:N-acetylglucosaminyltransferase I ⪡N-acetylglucosaminyltransferase II ⪡ galactosyltransferase. These results suggest a developmental regulation of the glycosyltransferases involved in oligosaccharide chain elongation of glycoproteins during intestinal cell differentiation.