The fate of Xenopus and locust vitellogenins made in Xenopus oocytes. An export-import processing model.
The fate of Xenopus and locust vitellogenins made in Xenopus oocytes. An export-import processing model.
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非洲爪蟾和非洲爪蟾卵母细胞中产生的蝗虫卵黄蛋白的命运。
DOI：
10.1111/j.1432-1033.1983.tb07182.x
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
S. Applebaum
中科院分区：
文献类型：
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作者：
C. Lane;J. Champion;A. Colman;T. James;S. Applebaum
非洲爪蟾肝脏或蝗虫脂肪体RNA注入非洲爪蟾卵母细胞指导形成的高分子量的物种，这是发现在卵母细胞内的膜泡部分短暂。这种内部产生的非洲爪蟾卵黄蛋白原向卵黄血小板蛋白的转化通过在孵育培养基中存在抗卵黄蛋白原抗体、或衣霉素、或秋水仙素和细胞胆素的混合物而减少。但是通过去除卵母细胞周围的滤泡层，输出和转化都不会被阻断。此外，周围的mRNA注射的去卵泡卵母细胞与过量的小去卵泡卵母细胞导致卵黄脂磷蛋白的积累减少的细胞，使卵黄蛋白原和未注射的饲养细胞的血小板中的卵黄脂磷蛋白的外观。
我们建议，新制作的蝗虫和非洲爪蟾卵黄蛋白被隔离在囊泡，然后由卵母细胞分泌，蝗虫物种被进一步修改分裂出口前。因此，异源卵黄前体的加工遵循用于制备供体RNA的细胞类型的途径特征。我们建议，进口机制之间的出口蝗虫和青蛙蛋白质的歧视，只有非洲爪蟾卵黄蛋白原随后进入卵母细胞，在那里它被转换为卵黄脂蛋白和卵黄蛋白由酶存在于蛋黄血小板。因此，我们解释了内部产生的和外部提供的青蛙卵黄蛋白原都转化为蛋黄血小板蛋白，而注射卵黄蛋白原不是明显矛盾的意见。
Xenopus liver or locust fat body RNA injected into Xenopus oocytes directs the formation of a high-molecular-weight species which is found transiently within the oocyte in a membranous vesicle fraction. The conversion of such internally generated Xenopus vitellogenin to yolk platelet proteins is reduced by the presence in the incubation medium of anti-vitellogenin antibodies, or of tunicamycin, or of a mixture of colchicine and cytocholasin. but neither export nor conversion is blocked by removal of the follicular layers which surround the oocyte. Moreover, surrounding mRNA injected defolliculated oocytes with an excess of small defolliculated oocytes leads to a reduction in lipovitellin accumulation in the cells making vitellogenin and the appearance of lipovitellin in the platelets of the uninjected feeder cells.
We propose that newly-made locust and Xenopus vitellogenins are sequestered in vesicles and are then secreted by the oocyte, the locust species being further modified by cleavage just before export. Thus processing of heterologous yolk precursors follows the pathway characteristic of the cell type used to prepare the donor RNA. We suggest that the import mechanism discriminates between the exported locust and frog proteins, and that only the Xenopus vitellogenin subsequently enters the oocyte, where it is converted to lipovitellin and phosvitin by an enzyme present in the yolk platelets. Thus we explain the apparently paradoxical observations that internally generated and externally supplied frog vitellogenin are both converted to yolk platelet proteins, whilst injected vitellogenin is not.