非洲爪蟾卵提取物中环形片层及其核孔复合体的自发形成

Spontaneous Formation of Annulate Lamellae and nuclear pore complexes in Activated Xenopus Egg Extracts

用超薄切片电镜技术结合冰冻蚀刻方法观察到在活化的爪蟾卵提取物中环形片层能够自发地大量形成,核孔复合体的超微结构与天然的核孔复合体没有区别,表明核孔复合体的装配能够不依赖于染色质或DNA的诱导而独立进行。进一步研究发现,在上述非细胞体系中,核孔复合体的自发装配需要可溶性组份与膜泡部分的共同参与,说明核孔复合体这种蛋白质性质的细胞器与膜物质有很密切的关系。活化的非洲爪蟾卵提取物为我们深入研究核孔复合体的装配及环形片层与核被膜的关系提供了一个很好的实验模式。

Using electron microscopic techniques such as ultrathin sectioning and freeze-etching we have showed that annulate lamellae,a structure composed of double membrane cisternae studded with nuclear pore complexes, could spontaneously form in activated Xenopus egg extracts without exogenous chromatin or DNA.The ultra- structure of these nuclear pore complexes were identical to that of naturally existed ones,indicating that the as- sembly of nuclear pore complexes could be promoted independently of the participation of chromatin or DNA. Though nuclear pore complexes are mainly made up of various proteins,intact pore complexes only could form when both fractions of egg extracts-soluble fraction and membrane vesicles-were mixed together.From these observations we could conclude that the components of nuclear pore complexes would prefer membrane strut- tures to chromatin or DNA to assemble nuclear pore complexes in the process of nuclear reconstitution or annu- late lamellae formation.