"MUTANTA ALTERED IN GLYCOSYLATION OF SOLUBLE & MEMBRANE

这项研究的总体目标是勾勒出 蛋白质的糖基化和确定可能的生物学后果 糖基化受损。我们的方法是隔离和刻画 糖基化缺陷的哺乳动物细胞突变体。中国仓鼠卵巢 (CHO)细胞突变体可通过单步和多步选择来分离 程序和筛查程序。一旦被分离，酶 细胞系中的缺陷被确定，使我们能够编目各种 合成途径中的反应；随后，我们可以确定 特定反应中的变化对不同的 糖蛋白产品。例如，我们之前确定 由美国国立卫生研究院阿普里尔·R·罗宾斯博士分离的CHO细胞株B4-2-1存在缺陷， 缺乏甘露糖磷二醇合成酶活性。这间牢房 LINE是根据其改变的甘露糖6-磷酸被分离出来的 受体活性；这种受体是一种糖蛋白。最近，我们还 表明B4-2-1缺乏甘露糖磷酰视黄醇合成酶活性， 强烈暗示只有一种合成酶利用 以杜仲醇或视黄酸为底物。(A)

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)