RELATIONSHIP OF GIX ANTIGEN EXPRESSION TO THE GLYCOSYLATION OF MURINE LEUKEMIA-VIRUS GLYCOPROTEIN
RELATIONSHIP OF GIX ANTIGEN EXPRESSION TO THE GLYCOSYLATION OF MURINE LEUKEMIA-VIRUS GLYCOPROTEIN
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DOI：
10.1073/pnas.77.11.6420
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发表时间：
1980-01-01
期刊：
影响因子：
--
通讯作者：
ROBBINS, PW
中科院分区：
文献类型：
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作者：
ROSNER, MR;TUNG, JS;ROBBINS, PW
在某些小鼠品系的胸腺细胞表面上表达的GIX抗原是鼠白血病病毒（gp 70）的主要包膜糖蛋白的抗原决定簇。虽然GIX在一些似乎不含病毒的小鼠品系中表达，但也可以通过感染特定的鼠白血病病毒（称为GIX+）在GIX-小鼠中诱导抗原。研究了GIX表型不同的2种密切相关病毒的包膜基因产物。通过聚丙烯酰胺凝胶电泳和内切糖苷酶处理的包膜蛋白前体的分析表明，GIX+病毒蛋白含有6个寡糖链，而GIX-病毒蛋白含有7个。观察到的各糖基化包膜基因切割产物（gp 70）的凝胶电泳迁移率和糖肽谱的差异可能是由于GIX病毒gp 70上存在额外的寡糖链。未检测到包膜基因（p15 E）的非糖基化产物的表观MW之间的差异。这些结果表明，相对于GIX+病毒，GIX-病毒编码额外的糖基化位点，并且该寡糖链存在于包膜基因前体（Prenv）和主要切割产物（gp 70）上。最近对来自GIX表型不同的病毒基因组的选定RNase T1寡核苷酸的核苷酸序列分析同样表明，GIX-表型和额外的糖基化位点之间可能存在相关性。这2种不同方法的结果提高了gp 70上存在额外寡糖链可能直接或间接掩盖胸腺细胞和病毒感染细胞表面GIX抗原表达的可能性。
The GIX antigen, which is expressed on the surface of thymocytes of certain mouse strains, is an antigenic determinant of the major envelope glycoprotein of murine leukemia virus (gp70). Although GIX is expressed in some mouse strains that appear to be free of virus, the antigen can also be induced in GIX- mice by infection with particular murine leukemia viruses (termed GIX+). The envelope gene products from 2 closely related viruses that differ in their GIX phenotype were studied. Analysis of the envelope protein precursors by polyacrylamide gel electrophoresis and endoglycosidase treatment indicated that the GIX+ viral protein contained 6 oligosaccharide chains, whereas the GIX- viral protein contained 7. The observed differences in gel electrophoretic mobilities and glycopeptide profiles of the respective glycosylated envelope gene cleavage products (gp70) may be accounted for by the presence of an additional oligosaccharide chain on the gp70 of the GIX- virus. No differences between the apparent MW of the nonglycosylated product of the envelope gene (p15E) were detected. These results suggest that the GIX- virus codes for an extra glycosylation site relative to the GIX+ virus, and this oligosaccharide chain is present both on the envelope gene precursor (Prenv) and on the major cleavage product (gp70). Recent nucleotide sequence analyses of selected RNase T1 oligonucleotides from the genomes of viruses that differ in GIX phenotype have similarly suggested that there may be a correlation between the GIX- phenotype and an extra glycosylation site. The results of these 2 different approaches raise the possibility that the presence of an additional oligosaccharide chain on gp70 may, either directly or indirectly, mask the expression of the GIX antigen on the surfaces of thymocytes and virus-infected cells.