首页> 外文OA文献 >Amino acid sequences in the alpha 1 domain and not glycosylation are important in HLA-A2/beta 2-microglobulin association and cell surface expression.
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Amino acid sequences in the alpha 1 domain and not glycosylation are important in HLA-A2/beta 2-microglobulin association and cell surface expression.

机译:在HLA-A2 /β2-微球蛋白缔合和细胞表面表达中,α1结构域中的氨基酸序列而不是糖基化非常重要。

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摘要

The role of the single carbohydrate moiety present on the HLA-A2 molecule was studied by introducing several amino acid substitutions (by site-directed mutagenesis of the HLA-A2 gene) in the consensus glycosylation sequence Asn-X-Ser. Two different amino acid substitutions of the asparagine residue at position 86 (glutamine and aspartic acid) resulted in the synthesis of ca. 39,000-molecular-weight nonglycosylated heavy chains that were detected in the cytoplasm but not on the surface of mouse L-cell transfectants. However, a low level of surface expression was detected following transfection of human (rhabdomyosarcoma) cells or mouse L cells containing human beta 2-microglobulin. The defect in surface expression was not due to the absence of the glycan moiety, since the substitution of a glycine for a serine at amino acid 88 did not have the same drastic effect in the presence of human beta 2-microglobulin. These and other data suggest that the asparagine residue may play a critical role in the conformation of the HLA heavy chain and its interaction with beta 2-microglobulin. Immunofluorescence microscopy following permeabilization of the transfectants demonstrated that the unglycosylated HLA heavy chains are sequestered in an unidentified cellular compartment that is different from the Golgi structure.
机译:通过在共有糖基化序列Asn-X-Ser中引入几个氨基酸取代(通过HLA-A2基因的定点诱变)来研究存在于HLA-A2分子上的单个碳水化合物部分的作用。 86位天冬酰胺残基的两个不同氨基酸取代(谷氨酰胺和天冬氨酸)导致合成ca。在细胞质中检测到39,000分子量的非糖基化重链,但在小鼠L细胞转染子的表面未检测到。然而,在转染含有人β2-微球蛋白的人(横纹肌肉瘤)细胞或小鼠L细胞后,检测到低水平的表面表达。表面表达的缺陷不是由于不存在聚糖部分,因为在人β2-微球蛋白的存在下,用甘氨酸替代氨基酸88的丝氨酸没有相同的剧烈作用。这些和其他数据表明,天冬酰胺残基可能在HLA重链的构象及其与β2-微球蛋白的相互作用中起关键作用。转染子透化后的免疫荧光显微镜检查表明,未糖基化的HLA重链被隔离在与高尔基体结构不同的未知细胞区室中。

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