The poly-N-acetyllactosamines attached to lysosomal membrane glycoproteins are increased by the prolonged association with the Golgi complex.
The poly-N-acetyllactosamines attached to lysosomal membrane glycoproteins are increased by the prolonged association with the Golgi complex.
复制标题
DOI：
10.1016/s0021-9258(18)54481-1
复制
发表时间：
1991-12
期刊：
影响因子：
--
通讯作者：
W. C. Wang;N. Lee;D. Aoki;M. Fukuda;M. Fukuda
中科院分区：
文献类型：
--
作者：
W. C. Wang;N. Lee;D. Aoki;M. Fukuda;M. Fukuda
中性粒细胞和单核细胞上的聚-N-乙酰乳糖胺已被证明是内皮细胞和血小板上存在的各种选择素的配体。我们以前已经表明，只有有限数量的糖蛋白含有聚-N-乙酰乳糖胺，并发现溶酶体膜糖蛋白（灯）是携带聚-N-乙酰乳糖胺的主要糖蛋白。为了理解为什么只有某些糖蛋白可以被聚-N-乙酰基乳糖胺修饰的原因，我们已经利用了21摄氏度的孵育条件，这在以前被证明会导致在trans-Golgi的糖蛋白的积累。HL-60细胞在21或37 ℃下用[3H]半乳糖标记6或24 h，并免疫沉淀lamp-1和lamp-2。经十二烷基硫酸钠-聚丙烯酰胺凝胶电泳检查，21 ℃孵育的HL-60细胞的每个灯显示出比37 ℃孵育的细胞分离的更宽、更慢的迁移带。含有聚-N-乙酰乳糖胺的N-聚糖的数量，通过其与番茄凝集素柱的结合来估计，在21 ℃下孵育后比在37 ℃下孵育增加约30 - 50%。对内切β-半乳糖苷酶消化释放的寡糖的分析表明，在21 ℃孵育后，含有三个或更多个N-乙酰乳糖胺重复序列的侧链的量增加约100%，甲基化分析证实了这些结果。同样的分析和通过离子交换色谱法获得的结果也提供了证据，表明灯的N-聚糖在21摄氏度和37摄氏度的唾液酸化程度一样多。使用[35S]甲硫氨酸标记的脉冲追踪实验表明，在21 ℃下处理灯所需的时间比在37 ℃下长得多。因此，这些结果表明，在21 ℃下孵育导致灯在高尔基复合体内停留更长时间，并且这种更长的停留允许灯获得更多的聚乳糖胺聚糖。这些结果还表明，通过高尔基复合体移动所需的时间是聚-N-乙酰乳糖胺形成的关键因素。
The poly-N-acetyllactosamines on neutrophils and monocytes have been shown to serve as ligands for various selectins present on endothelial cells and platelets. We have previously shown that only a limited number of glycoproteins contain poly-N-acetyllactosamine and found that lysosomal membrane glycoproteins (lamps) are the major glycoproteins carrying poly-N-acetyllactosamine. In order to understand the reason why only certain glycoproteins can be modified by poly-N-acetyllactosamine, we have utilized 21 degrees C incubation conditions, which were previously shown to cause the accumulation of glycoproteins at the trans-Golgi. HL-60 cells were labeled with [3H]galactose at 21 or 37 degrees C for 6 or 24 h, and lamp-1 and lamp-2 were immunoprecipitated. Upon examination by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, each lamp from HL-60 cells incubated at 21 degrees C exhibited a much broader, slower migrating band than that isolated from the cells incubated at 37 degrees C. The number of N-glycans containing poly-N-acetyllactosamine, estimated by their binding to tomato lectin column, increased approximately 30-50% after incubation at 21 degrees C than incubation at 37 degrees C. The analysis of oligosaccharides released by endo-beta-galactosidase digestion demonstrates that the amount of side chains containing three or more N-acetyllactosamine repeats increased about 100% after incubation at 21 degrees C, and methylation analysis confirmed these results. The same analysis and the results obtained by ion-exchange chromatography also provided evidence that the N-glycans of lamps are sialylated at 21 degrees C as much as at 37 degrees C. Pulse-chase experiments using [35S]methionine labeling indicated that the time necessary for processing of lamps is much longer at 21 degrees C than at 37 degrees C. These results therefore indicate that incubation at 21 degrees C causes the lamps to reside longer within the Golgi complex, and such longer residence allows lamps to acquire more polylactosaminoglycan. These results also suggest that the time necessary for moving through the Golgi complex is a critical factor for poly-N-acetyllactosamine formation.