Dhugga K S, Ulvskov P, Gallagher S R, Ray P M
Department of Biological Sciences, Stanford University, California 94305.
J Biol Chem. 1991 Nov 15;266(32):21977-84.
In pea membranes, UDP[14C]Glc glycosylates a approximately 40-kDa polypeptide doublet. This label rapidly disappears if excess unlabeled UDP-Glc, or UDP, is added, indicating that the glycosylation is reversible, and suggesting that the glycosylated polypeptides might be intermediates in a glycosyl transfer reaction. Glycosylation of the doublet requires a divalent cation, the effective ions being the same (except for Zn2+) as those that activate Golgi-localized beta-glucan synthase (GS-I) activity. Treatments that inhibit GS-I also inhibit doublet glycosylation. The doublet is associated with Golgi (and to a minor extent with plasma) membranes and occurs also in the soluble fraction. The Golgi-bound doublet may be a component of the GS-I system. Immunological, inactivation, and fractionation evidence indicates that at least one other polypeptide is required in GS-I activity.
在豌豆膜中，UDP[14C]葡萄糖糖基化一种约40 kDa的多肽双峰。如果加入过量未标记的UDP-葡萄糖或UDP，这种标记会迅速消失，这表明糖基化是可逆的，并提示糖基化多肽可能是糖基转移反应中的中间体。该双峰的糖基化需要二价阳离子，除Zn2+外，有效离子与激活高尔基体定位的β-葡聚糖合酶（GS-I）活性的离子相同。抑制GS-I的处理也会抑制双峰糖基化。该双峰与高尔基体（在较小程度上与质膜）相关，也存在于可溶性部分中。与高尔基体结合的双峰可能是GS-I系统的一个组成部分。免疫学、失活和分级分离证据表明，GS-I活性至少还需要一种其他多肽。
