Piller F, Piller V, Fox R I, Fukuda M
Cancer Research Center, La Jolla Cancer Research Foundation, California.
J Biol Chem. 1988 Oct 15;263(29):15146-50.
The activation of human T-lymphocytes by anti-CD3 antibodies and interleukin-2 results in a marked increase in apparent molecular weight of the major cell-surface sialoglycoprotein. Both forms of the sialoglycoprotein were identified as leukosialin by a monospecific antiserum, and the differences in molecular weight were found to be due to changes in the carbohydrate structures. Our results suggest that resting T-lymphocytes express on leukosialin the disialotetrasaccharides NeuNAc alpha 2----3Gal beta 1----3(NeuNAc alpha 2----6)Gal-NAc-Ser/Thr, whereas activated human T-cells carry on leukosialin exclusively the more complex structures NeuNAc alpha 2----3Gal beta 1----3(NeuNAc alpha 2----3Gal beta 1----4GlcNAc beta 1----6)GalNAc-Ser/Thr. The radical shift in the biosynthetic pathway of O-glycans in activated T-lymphocytes compared to resting cells is apparently caused by a decrease of alpha 2----6 sialyltransferase activity and by the parallel dramatic stimulation of the beta 1----6GlcNAc-transferase. Since both enzymes compete for the same precursor substrate, the coordinate changes in their activities are most likely responsible for the complete change of the carbohydrate structures on leukosialin during the activation of human T-lymphocytes.
抗CD3抗体和白细胞介素-2激活人T淋巴细胞会导致主要细胞表面唾液酸糖蛋白的表观分子量显著增加。两种形式的唾液酸糖蛋白均被一种单特异性抗血清鉴定为白细胞唾液酸蛋白，且分子量的差异被发现是由于碳水化合物结构的变化所致。我们的结果表明，静止T淋巴细胞在白细胞唾液酸蛋白上表达二唾液酸四糖NeuNAcα2----3Galβ1----3(NeuNAcα2----6)Gal-NAc-Ser/Thr，而活化的人T细胞在白细胞唾液酸蛋白上仅携带更为复杂的结构NeuNAcα2----3Galβ1----3(NeuNAcα2----3Galβ1----4GlcNAcβ1----6)GalNAc-Ser/Thr。与静止细胞相比，活化T淋巴细胞中O-聚糖生物合成途径的根本转变显然是由α2----6唾液酸转移酶活性降低以及β1----6GlcNAc转移酶同时受到显著刺激所致。由于这两种酶竞争相同的前体底物，它们活性的协同变化很可能是人T淋巴细胞活化过程中白细胞唾液酸蛋白上碳水化合物结构完全改变的原因。
