Hurt E C
European Molecular Biology Laboratory, Heidelberg, Federal Republic of Germany.
J Cell Biol. 1990 Dec;111(6 Pt 2):2829-37. doi: 10.1083/jcb.111.6.2829.
The yeast nuclear envelope protein NSP1 is located at the nuclear pores and mediates its essential function via the carboxy-terminal domain. The passenger protein, cytosolic dihydrofolate reductase from mouse, was fused to the 220 residue long NSP1 carboxy-terminal domain. When expressed in yeast, this chimeric protein was tightly associated with nuclear structures and was localized at the nuclear periphery very similar to authentic NSP1. Furthermore, the DHFR-C-NSP1 fusion protein was able to complement a yeast mutant lacking a functional NSP1 gene showing that DHFR-C-NSP1 fulfils the same basic function as compared to the endogenous NSP1 protein. These data also show that the NSP1 protein is composed of separate functional moieties: a carboxy-terminal domain that is sufficient to mediate the association with the nuclear periphery and an amino-terminal and middle repetitive domain with an as yet unknown function. It is suggested that heptad repeats found in the NSP1 carboxy-terminal domain, which are similar to those found in intermediate filament proteins, are crucial for mediating the association with the nuclear pores.
酵母核膜蛋白NSP1位于核孔处，并通过其羧基末端结构域介导其重要功能。乘客蛋白，即来自小鼠的胞质二氢叶酸还原酶，与220个残基长的NSP1羧基末端结构域融合。当在酵母中表达时，这种嵌合蛋白与核结构紧密相关，并定位于核周，与天然NSP1非常相似。此外，DHFR-C-NSP1融合蛋白能够补充缺乏功能性NSP1基因的酵母突变体，表明与内源性NSP蛋白相比，DHFR-C-NSP1具有相同的基本功能。这些数据还表明，NSP1蛋白由独立的功能部分组成：一个足以介导与核周结合的羧基末端结构域，以及一个功能未知的氨基末端和中间重复结构域。有人认为，在NSP1羧基末端结构域中发现的七肽重复序列，与中间丝蛋白中的七肽重复序列相似，对于介导与核孔的结合至关重要。
