Characterization of Karyopherin Cargoes Reveals Unique Mechanisms of Kap121p-Mediated Nuclear Import
AUTOR(ES)
Leslie, Deena M.
FONTE
American Society for Microbiology
RESUMO
In yeast there are at least 14 members of the β-karyopherin protein family that govern the movement of a diverse set of cargoes between the nucleus and cytoplasm. Knowledge of the cargoes carried by each karyopherin and insight into the mechanisms of transport are fundamental to understanding constitutive and regulated transport and elucidating how they impact normal cellular functions. Here, we have focused on the identification of nuclear import cargoes for the essential yeast β-karyopherin, Kap121p. Using an overlay blot assay and coimmunopurification studies, we have identified 30 putative Kap121p cargoes. Among these were Nop1p and Sof1p, two essential trans-acting protein factors required at the early stages of ribosome biogenesis. Characterization of the Kap121p-Nop1p and Kap121p-Sof1p interactions demonstrated that, in addition to lysine-rich nuclear localization signals (NLSs), Kap121p recognizes a unique class of signals distinguished by the abundance of arginine and glycine residues and consequently termed rg-NLSs. Kap104p is also known to recognize rg-NLSs, and here we show that it compensates for the loss of Kap121p function. Sof1p is also transported by Kap121p; however, its import can be mediated by a piggyback mechanism with Nop1p bridging the interaction between Sof1p and Kap121p. Together, our data elucidate additional levels of complexity in these nuclear transport pathways.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=516728Documentos Relacionados
- Characterization of Karyopherin Cargoes Reveals Unique Mechanisms of Kap121p-Mediated Nuclear Import
- Kap121p-Mediated Nuclear Import Is Required for Mating and Cellular Differentiation in Yeast
- Intersection of the Kap123p-Mediated Nuclear Import and Ribosome Export Pathways
- The importin/karyopherin Kap114 mediates the nuclear import of TATA-binding protein
- The Intracellular Mobility of Nuclear Import Receptors and NLS Cargoes