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The adapter importin-α provides flexible control of nuclear import at the expense of efficiency
Although there exists a large family of nuclear transport receptors (Karyopherins), the majority of known import cargoes use an adapter protein, Importin-α (Impα), which links the cargo to a karyopherin, Importin-β (Impβ). The reason for the existence of transport adapters is unknown. One hypothesis...
Autores principales: | , |
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Formato: | Texto |
Lenguaje: | English |
Publicado: |
Nature Publishing Group
2007
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1911202/ https://www.ncbi.nlm.nih.gov/pubmed/17551513 http://dx.doi.org/10.1038/msb4100160 |
Sumario: | Although there exists a large family of nuclear transport receptors (Karyopherins), the majority of known import cargoes use an adapter protein, Importin-α (Impα), which links the cargo to a karyopherin, Importin-β (Impβ). The reason for the existence of transport adapters is unknown. One hypothesis is that, as Impα re-export is coupled to GTP hydrolysis, it can drive a higher concentration of nuclear cargo than could be achieved by direct cargo binding to Importin-β. However, computer simulations predicted the opposite outcome, and showed that direct transport is faster than adapter-mediated transport. These predictions were validated experimentally. The data, together with previous analyses of nuclear protein import, suggest that the use of adapters such as importin-α provides the cell with increased dynamic range for control of nuclear import rates, but at the expense of efficiency. |
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