MUTANTS ALTERED IN GLYCOSYLATION OF SOLUBLE & MEMBRANE

本研究的总体目标是描绘出 蛋白质的糖基化，并确定可能的生物学后果 受损的糖基化。 我们的方法是分离并描述 糖基化缺陷的哺乳动物细胞突变体。 中国仓鼠卵巢 (CHO)通过单步和多步选择分离细胞突变体 程序和筛选程序。 一旦分离，酶 确定细胞系中的缺陷，使我们能够对各种 合成途径中的反应;随后，我们可以确定 特定反应中的改变对不同反应的影响 糖蛋白产物。 例如，我们先前确定， 缺陷B4-2-1，CHO细胞系分离的博士四月R。罗宾斯，国家卫生研究院， 缺乏甘露糖基磷酸多醇合酶活性。 该细胞 已根据其改变的甘露糖6-磷酸分离了一个品系 受体活性;该受体是糖蛋白。 最近，我们还 显示B4-2-1缺乏甘露糖基磷酸视黄醇合酶活性， 这强烈暗示只有一种合酶利用 长叶醇或视黄基磷酸酯作为底物。 （一）

The general aim of this research is to delineate the various steps in the glycosylation of proteins and to determine possible biological consequences of impaired glycosylation. Our approach is to isolate and characterize mammalian cell mutants defective in glycosylation. Chinese hamster ovary (CHO) cell mutants are isolated by both single and multistep selection procedures and by screening procedures. Once isolated, the enzymatic defect in the cell line is determined, allowing us to catalog various reactions in the synthetic pathway; subsequently, we can determine what effect the alteration in a particular reaction has on different glycoprotein products. For example, we previously determined that the defect in B4-2-1, a CHO cell line isolated by Dr. April R. Robbins, NIH, was the lack of mannosylphosphoryldolichol synthase activity. This cell line had been isolated on the basis of its altered mannose 6-phosphate receptor activity; this receptor is a glycoprotein. Recently, we have also shown that B4-2-1 lacks mannosylphosphorylretinol synthase activity, strongly implying that there is only one synthase that utilizes either dolichyl or retinyl phosphate as substrate. (A)