Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, Campus de Gualtar, Braga, Portugal.
PLoS One. 2011 Feb 9;6(2):e16846. doi: 10.1371/journal.pone.0016846.
The Karyopherin (Kap) family of nuclear transport receptors enables trafficking of proteins to and from the nucleus in a precise, regulated manner. Individual members function in overlapping pathways, while simultaneously being very specific for their main cargoes. The details of this apparent contradiction and rules governing pathway preference remain to be further elucidated. S. cerevisiae Lhp1 is an abundant protein that functions as an RNA chaperone in a variety of biologically important processes. It localizes almost exclusively to the nucleus and is imported by Kap108. We show that mutation of 3 of the 275 residues in Lhp1 alters its import pathway to a Kap121-dependent process. This mutant does not retain wild-type function and is bound by several chaperones. We propose that Kap121 also acts as a chaperone, one that can act as a genetic buffer by transporting mutated proteins to the nucleus.
核输入蛋白 (Kap) 家族是一类核转运受体，能够以精确、受调控的方式将蛋白质运输到细胞核或从细胞核输出。各个成员在重叠的途径中发挥作用，同时对其主要货物具有非常特异性。这种明显的矛盾的细节和决定途径偏好的规则仍有待进一步阐明。酿酒酵母 Lhp1 是一种丰富的蛋白质，在多种重要的生物学过程中作为 RNA 伴侣发挥作用。它几乎完全定位于细胞核内，并由 Kap108 导入。我们发现，Lhp1 中 275 个残基中的 3 个突变改变了其导入途径，变为依赖于 Kap121 的过程。这种突变体不能保留野生型功能，并且被几种伴侣蛋白结合。我们提出 Kap121 也作为伴侣蛋白发挥作用，它可以通过将突变蛋白运输到细胞核来充当遗传缓冲剂。
