Wiederschain G Y, Koul O, Aucoin J M, Smith F I, McCluer R H
Department of Biomedical Sciences, E.K. Shriver Center, Waltham, MA 02254, USA.
Glycoconj J. 1998 Apr;15(4):379-88. doi: 10.1023/a:1006925918978.
Fucosyltransferases (FTs) and various glycosidases that are involved in the biosynthesis or degradation of SSEA-1 (Le(x)) antigens and their precursors in the CNS are developmentally regulated. In forebrain and cerebellum with lactosamine (LacNAc) as acceptor the FT activity was maximal at P15-P22, but with the glycolipid substrate paragloboside (nLc4) the maximal activity in cerebellum was obtained at P10-P15. The FT activity, with these substrates, was insensitive to N-ethylmaleimide (NEM) and the glycolipid product had an alpha1,3 linkage (Fuc to GlcNAc) suggesting similarities of the investigated enzyme to the cloned human and rat FT IV. However, the observation of different patterns of FT activity in isoelectrofocused fractions (pH 3.5-10) with different types of acceptors, and the differential expression of Le(x) containing glycolipids and glycoproteins during development strongly suggest the presence of more than one type of FT during development. Data on developmental expression of the hydrolytic enzymes, alpha-L-fucosidase, beta-D-galactosidase and alpha-D-galactosidase, which can potentially hydrolyse SSEA-1 or its precursors, support the notion that SSEA-1 expression is the result of a dynamic balance between the activity of transferases and hydrolases.
岩藻糖基转移酶（FTs）以及参与中枢神经系统中阶段特异性胚胎抗原-1（SSEA-1，Le(x)）抗原及其前体生物合成或降解的各种糖苷酶受发育调控。在前脑和小脑中，以乳糖胺（LacNAc）为受体时，FT活性在出生后15至22天达到最大值，但以糖脂底物副球蛋白（nLc4）时，小脑的最大活性在出生后10至15天获得。这些底物的FT活性对N-乙基马来酰亚胺（NEM）不敏感，且糖脂产物具有α1,3连接（岩藻糖与N-乙酰葡糖胺），这表明所研究的酶与克隆的人及大鼠FT IV具有相似性。然而，在等电聚焦组分（pH 3.5 - 10）中观察到不同类型受体的FT活性模式不同，以及发育过程中含Le(x)的糖脂和糖蛋白的差异表达，强烈表明发育过程中存在不止一种类型的FT。关于水解酶α-L-岩藻糖苷酶、β-D-半乳糖苷酶和α-D-半乳糖苷酶发育表达的数据，这些酶可能水解SSEA-1或其前体，支持了SSEA-1表达是转移酶和水解酶活性之间动态平衡结果的观点。
