Soniat Michael, Sampathkumar Parthasarathy, Collett Garen, Gizzi Anthony S, Banu Radhika N, Bhosle Rahul C, Chamala Swetha, Chowdhury Sukanya, Fiser Andras, Glenn Alan S, Hammonds James, Hillerich Brandan, Khafizov Kamil, Love James D, Matikainen Bridget, Seidel Ronald D, Toro Rafael, Rajesh Kumar P, Bonanno Jeffery B, Chook Yuh Min, Almo Steven C
Department of Pharmacology, University of Texas Southwestern, Dallas, TX 75390, USA.
J Struct Funct Genomics. 2013 Jun;14(2):31-5. doi: 10.1007/s10969-013-9150-1. Epub 2013 Mar 28.
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.
输入核转运蛋白或输入蛋白通过结合核定位信号（NLS）来介导蛋白质进入细胞核。核转运蛋白β2（Kapβ2），也称为运输蛋白，是该转运蛋白家族的成员之一，负责众多RNA结合蛋白的输入。Kapβ2识别位于其货物内的一种称为PY-NLS的靶向信号，以通过核孔复合体将它们靶向运输。Kapβ2对PY-NLS的识别在整个真核生物中都是保守的。酿酒酵母中的Kapβ2同源物Kap104识别货物Nab2、Hrp1和Tfg2中的PY-NLS。我们已经确定了与mRNA加工蛋白Nab2的PY-NLS结合的Kapβ2的晶体结构，分辨率为3.05埃。观察到Nab2的PY-NLS的一个七残基片段以伸展构象结合Kapβ2，并占据在其他Kapβ2·PY-NLS结构中观察到的相同的PY-NLS结合位点。
