Poly-N-acetyllactosaminyl O-glycans attached to leukosialin. The presence of sialyl Le(x) structures in O-glycans.
Poly-N-acetyllactosaminyl O-glycans attached to leukosialin. The presence of sialyl Le(x) structures in O-glycans.
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DOI：
10.1016/s0021-9258(18)35777-6
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发表时间：
1992-12
期刊：
影响因子：
--
通讯作者：
K. Maemura;M. Fukuda
中科院分区：
文献类型：
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作者：
K. Maemura;M. Fukuda
除了 N-聚糖和鞘糖脂外，在 O-聚糖中也发现了聚-N-乙酰基乳糖胺延伸。尝试在 HL-60 和 K562 细胞中测定主要唾液酸糖蛋白白唾液酸蛋白中聚 N-乙酰基乳糖胺基 O-聚糖的含量。从[3H]葡萄糖胺标记的 HL-60 和 K562 细胞中免疫沉淀白唾液酸蛋白。通过链霉蛋白酶消化制备糖肽，并使用Jacalin-琼脂糖通过亲和层析分离含O-聚糖的糖肽。用碱性硼氢化物处理与 Jacalin-琼脂糖结合的糖肽和未结合的糖肽，并通过 Bio-Gel P-4 过滤对释放的 O-聚糖进行分级。 O-聚糖的连续糖苷酶消化，无论是否经过岩藻糖苷酶或神经氨酸酶预处理，揭示了以下结论。 1) 来自 HL-60 细胞的白唾液酸蛋白含有约 1-2 个聚-N-乙酰基乳糖胺基 O-聚糖链/分子。 2) 大约 50% 的这些聚-N-乙酰基乳糖胺基 O-聚糖含有唾液酸 Le(x) 末端，NeuNAc α 2–>3Gal beta 1–>4 (Fuc α 1–>3)GlcNAc beta 1–>R。白唾液酸蛋白中唾液酸化Le(x)结构的量与HL-60细胞表面的唾液酸化Le(x)结构的量大致相当。 3) 另一方面，来自 K562 细胞的白唾液酸蛋白不含可检测量的聚-N-乙酰基乳糖胺基 O-聚糖。 4) O-聚糖中聚-N-乙酰基乳糖胺的存在取决于核心2β1,6-N-乙酰氨基葡萄糖转移酶。 5) Jacalin-琼脂糖与唾液酸化小寡糖结合，例如 NeuNAc α 2–>3Gal beta 1–>3(NeuNAc α 2–>6) GalNAc，但不与六糖 NeuNAc α 2–>3Gal beta 1–>3(NeuNAc α 2–>3Gal beta 1–>4GlcNAc beta 1–>6) GalNAc 结合。这些结果表明，O-聚糖中聚乳糖胺基O-聚糖和唾液酸Le(x)结构的形成取决于核心2的形成。
Poly-N-acetyllactosamine extension has been found in O-glycans in addition to N-glycans and glycosphingolipids. Attempts were made in HL-60 and K562 cells to determine the amount of poly-N-acetyllactosaminyl O-glycans in the major sialoglycoprotein, leukosialin. Leukosialin was immunoprecipitated from [3H]glucosamine-labeled HL-60 and K562 cells. Glycopeptides were prepared by Pronase digestion, and O-glycan-containing glycopeptides were isolated by affinity chromatography using Jacalin-agarose. The glycopeptides bound to Jacalin-agarose and those unbound were treated with alkaline borohydride, and the released O-glycans were fractionated by Bio-Gel P-4 filtration. Sequential glycosidase digestion of the O-glycans, with or without pretreatment by fucosidase or neuraminidase, revealed the following conclusions. 1) Leukosialin from HL-60 cells contains about 1-2 poly-N-acetyllactosaminyl O-glycan chains/molecule. 2) About 50% of these poly-N-acetyllactosaminyl O-glycans contain sialyl Le(x) termini, NeuNAc alpha 2–>3Gal beta 1–>4 (Fuc alpha 1–>3)GlcNAc beta 1–>R. The amount of sialyl Le(x) structure in leukosialin is roughly equivalent to that on cell surfaces of HL-60 cells. 3) Leukosialin from K562 cells, on the other hand, contains no detectable amount of poly-N-acetyllactosaminyl O-glycans. 4) The presence of poly-N-acetyllactosamine in O-glycans is dependent on the core 2 beta 1,6-N-acetylglucosaminyl transferase. 5) Jacalin-agarose binds to sialylated small oligosaccharides such as NeuNAc alpha 2–>3Gal beta 1–>3(NeuNAc alpha 2–>6) GalNAc but not the hexasaccharide NeuNAc alpha 2–>3Gal beta 1–>3(NeuNAc alpha 2–>3Gal beta 1–>4GlcNAc beta 1–>6) GalNAc. These results indicate that the formation of polylactosaminyl O-glycans and sialyl Le(x) structure in O-glycans is dependent on the core 2 formation.