Importin β3 mediates the nuclear import of human ribosomal protein L7 through its interaction with the multifaceted basic clusters of L7

Abstract

Edited by Ulrike Kutay Keywords:Eukaryotic ribosomal protein L7 Importin b3 Nuclear localization signal (NLS) Biosensor Overlay assay Fluorescence recovery after photobleaching (FRAP) assay a b s t r a c tWe show that importin b3 is essential for the nuclear import of L7. The import is mediated via the multifaceted basic amino acid clusters present in the NH 2 -region of L7, and is RanGTP-dependent. Using a (EGFP) 3 reporter system and a FRAP assay, the role the individual clusters play as a functional NLS has been characterized, and each cluster was found to exhibit a different rate of real time nuclear uptake. We assume that having such a multiple NLS may provide L7 with preferential nuclear uptake.

LAS1L interacts with the mammalian Rix1 complex to regulate ribosome biogenesis

“…Another protein found to interact with LAS1L in this study is RanBP5 (Figure 2A), a karyopherin β that associates with the nuclear pore complex to facilitate the import of both small and large ribosomal proteins (Jakel and Gorlich, 1998; Chou et al , 2010). RanBP5 is homologous with the karyopherin-β proteins Pse1p/Kap121p and Yrb4p/Kap123p in S. cerevisiae .…”

“…Interestingly, PELP1 shares some sequence homology with Rix1p and, therefore, with TEX10 and WDR18, represents the mammalian counterpart of the budding yeast Rix1 complex (Finkbeiner et al , 2011). RanBP5 is a karyopherin-β protein that has been shown to mediate nuclear import of ribosomal proteins (Jakel and Gorlich, 1998; Chou et al , 2010). NOL9 was recently described as a 5′-polynucleotide kinase required for processing of the ITS-2 region of rRNA (Heindl and Martinez, 2010), while SENP3 is a nucleolar SUMO-specific protease shown to be required for both ITS-2 pre-rRNA processing and SUMO deconjugation of ribosomal proteins and NPM1 (Gong and Yeh, 2006; Haindl et al , 2008; Yun et al , 2008).…”

“…Identified proteins are marked with arrows. (B) The proteins identified in (A) and their corresponding S. cerevisiae putative homologues (Rout et al , 1997; Jakel and Gorlich, 1998; Bassler et al , 2001; Vadlamudi et al , 2001, 2004; Peng et al , 2003; Galani et al , 2004; Krogan et al , 2004; Gong and Yeh, 2006; Panse et al , 2006; Nair et al , 2007; Haindl et al , 2008; Yun et al , 2008; Braglia et al , 2010; Chou et al , 2010; Heindl and Martinez, 2010; Finkbeiner et al , 2011). …”

Dengue virus NS1 protein interacts with the ribosomal protein RPL18: This interaction is required for viral translation and replication in Huh-7 cells

“…Additionally, the RPL7 has been involved in the anchoring of the ribosome to the endoplasmic reticulum membranes (Wu et al, 2007). Additionally, since RPL7 contains multifaceted basic amino acid clusters present in the NH( 2 )-region of the protein it can interacts with importin β3 which is essential for the nuclear import of RPL7 (Chou et al, 2010).…”

The N-terminal extension of yeast ribosomal protein L8 is involved in two major remodeling events during late nuclear stages of 60S ribosomal subunit assembly

“…This result was not surprising considering that this unusual extension is likely to affect folding of the globular region of L7. Moreover, the N-terminus of L7 was previously shown to contain monopartite and bipartite nuclear localization sequences, deletion of which could prevent nuclear import and assembly of L7, leading to its turnover (Chou et al 2010;Tai et al 2013). Since destabilization of L7 is the same as its depletion, these truncation mutations do not provide any novel information about potential roles of the L7 extension and were not studied further.…”