Green E D, Boime I, Baenziger J U
J Biol Chem. 1986 Dec 15;261(35):16309-16.
The asparagine-linked oligosaccharides on bovine lutropin (bLH) are unusual, containing GalNAc and sulfate but no galactose or sialic acid. Oligosaccharides from metabolically radiolabeled or purified bLH consist of non- (neutral), mono- (S-1), and di- (S-2) sulfated structures. We have previously shown that S-2 is a complex type oligosaccharide bearing two peripheral branches with the sequence SO4----GalNAc----GlcNAc attached to a typical Man3GlcNAc2 core (Green, E.D., van Halbeek, H., Boime, I., and Baenziger, J.U. (1985) J. Biol. Chem. 260, 15623-15630). We have now characterized the S-1 oligosaccharides on bLH which, in contrast to S-2, consist of several different structures of both the hybrid and complex types. The sulfate on S-1 oligosaccharides is located exclusively within the peripheral sequence SO4----GalNAc----GlcNAc. The GalNAc bearing hybrid structures, either with or without sulfate, cannot be processed to mono- or disulfated complex oligosaccharides due to the inability of either alpha-mannosidase II or GlcNAc-transferase II to act on GalNAc containing oligosaccharides. Since both Gal and GalNAc are added to oligosaccharides on some pituitary hormones, for example bovine and ovine follitropin and human lutropin, the Gal- and GalNAc-transferases appear to be key elements in regulating the synthesis of sulfated oligosaccharides on bLH and the other pituitary glycoprotein hormones.
牛促黄体激素（bLH）上的天冬酰胺连接型寡糖不同寻常，含有N-乙酰半乳糖胺（GalNAc）和硫酸根，但不含半乳糖或唾液酸。来自代谢性放射性标记或纯化的bLH的寡糖由非硫酸化（中性）、单硫酸化（S-1）和双硫酸化（S-2）结构组成。我们之前已经表明，S-2是一种复合型寡糖，带有两个外围分支，其序列为SO4----GalNAc----GlcNAc，连接到一个典型的Man3GlcNAc2核心上（格林，E.D.，范·哈尔贝克，H.，博伊姆，I.，以及贝恩齐格，J.U.（1985年）《生物化学杂志》260，15623 - 15630）。我们现在已经对bLH上S-1寡糖进行了表征，与S-2不同，S-1寡糖由几种不同的杂合型和复合型结构组成。S-1寡糖上的硫酸根仅位于外围序列SO4----GalNAc----GlcNAc内。带有杂合结构的GalNAc，无论有无硫酸根，都不能被加工成单硫酸化或双硫酸化的复合型寡糖，因为α-甘露糖苷酶II或N-乙酰葡糖胺转移酶II都无法作用于含有GalNAc的寡糖。由于半乳糖（Gal）和N-乙酰半乳糖胺（GalNAc）都会添加到某些垂体激素的寡糖上，例如牛和羊的促卵泡激素以及人促黄体激素，所以Gal-和GalNAc-转移酶似乎是调节bLH和其他垂体糖蛋白激素上硫酸化寡糖合成的关键因素。
