Abstract
Import-Karyopherin or Importin proteins bind nuclear localization signals (NLSs) to mediate the import of proteins into the cell nucleus. Karyopherin β2 or Kapβ2, also known as Transportin, is a member of this transporter family responsible for the import of numerous RNA binding proteins. Kapβ2 recognizes a targeting signal termed the PY-NLS that lies within its cargos to target them through the nuclear pore complex. The recognition of PY-NLS by Kapβ2 is conserved throughout eukaryotes. Kap104, the Kapβ2 homolog in Saccharomyces cerevisiae, recognizes PY-NLSs in cargos Nab2, Hrp1, and Tfg2. We have determined the crystal structure of Kapβ2 bound to the PY-NLS of the mRNA processing protein Nab2 at 3.05-Å resolution. A seven-residue segment of the PY-NLS of Nab2 is observed to bind Kapβ2 in an extended conformation and occupies the same PY-NLS binding site observed in other Kapβ2·PY-NLS structures.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Amino Acid Sequence
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Binding Sites
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Cell Nucleus / metabolism
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Crystallography, X-Ray
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Humans
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Hydrophobic and Hydrophilic Interactions
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Molecular Sequence Data
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Nuclear Localization Signals / chemistry*
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Nuclear Localization Signals / metabolism
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Nucleocytoplasmic Transport Proteins / chemistry*
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Nucleocytoplasmic Transport Proteins / metabolism
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RNA, Messenger / metabolism
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RNA-Binding Proteins / chemistry*
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RNA-Binding Proteins / metabolism
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins / chemistry*
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Saccharomyces cerevisiae Proteins / metabolism
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beta Karyopherins / chemistry*
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beta Karyopherins / metabolism
Substances
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NAB2 protein, S cerevisiae
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Nuclear Localization Signals
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Nucleocytoplasmic Transport Proteins
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RNA, Messenger
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RNA-Binding Proteins
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Saccharomyces cerevisiae Proteins
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TNPO1 protein, human
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beta Karyopherins