Krohne G, Stuurman N, Kempf A
Division of Electron Microscopy, Biocenter of the University of Würzburg, Germany.
Eur J Cell Biol. 1998 Dec;77(4):276-83. doi: 10.1016/S0171-9335(98)80086-1.
Despite extensive knowledge of the in vitro polymerization properties of nuclear lamins, it is still not well understood how the nuclear lamina assembles in vivo. To learn more about the relationship between in vitro and in vivo polymerization of nuclear lamins, we expressed Drosophila lamin Dm0, mutant proteins, having well defined alterations of their in vitro polymerization properties, in Sf9 cells using the baculovirus system. All lamin Dm0 mutants assembled into fibrillar aggregates indistinguishable in morphology from those assembled by the wild-type protein. However, in contrast to wild-type lamin Dm0, mutant proteins were extracted with buffers of physiological ionic strength and pH containing Triton X-100. These results indicate that various types of lamin dimer-dimer interactions can be disrupted without affecting the morphology of the lamin Dm0 polymer. However, all types of dimer-dimer interactions tested appear to be important for full polymer stability. In addition, we analyzed the polymer formation of two Drosophila lamin C mutants and found that a segment in the carboxy-terminal tail domain is required for assembly of lamin C paracrystals at the nuclear lamina.
尽管对核纤层蛋白的体外聚合特性已有广泛了解，但核纤层在体内如何组装仍未得到很好的理解。为了更多地了解核纤层蛋白体外和体内聚合之间的关系，我们使用杆状病毒系统在Sf9细胞中表达了果蝇核纤层蛋白Dm0及其突变蛋白，这些突变蛋白的体外聚合特性有明确的改变。所有的核纤层蛋白Dm0突变体都组装成了纤维状聚集体，其形态与野生型蛋白组装的聚集体无法区分。然而，与野生型核纤层蛋白Dm0不同，突变蛋白可以用含有Triton X-100的生理离子强度和pH值的缓冲液提取。这些结果表明，各种类型的核纤层蛋白二聚体-二聚体相互作用可以被破坏，而不影响核纤层蛋白Dm0聚合物的形态。然而，所测试的所有类型的二聚体-二聚体相互作用似乎对聚合物的完全稳定性都很重要。此外，我们分析了两种果蝇核纤层蛋白C突变体的聚合物形成，发现羧基末端尾部结构域中的一个片段是核纤层蛋白C在核纤层组装成准晶体所必需的。
