Parrott Andrew M, Walsh Melissa R, Reichman Trevor W, Mathews Michael B
Department of Biochemistry and Molecular Biology and New Jersey Medical School, UMDNJ, 185 South Orange Ave., P.O. Box 1709, Newark, NJ 07101-1709, USA.
J Mol Biol. 2005 Apr 29;348(2):281-93. doi: 10.1016/j.jmb.2005.02.047.
Members of the nuclear factor 90 (NF90) family of human double-stranded RNA (dsRNA) binding proteins are phosphorylated and translocate into the cytoplasm with the onset of mitosis. We investigated the mechanism of translocation for NF90 and NF110, its larger splice variant. During interphase, NF90 is predominantly nuclear, NF110 is exclusively nuclear, and both are bound to RNA. About half of the NF90 is tethered in the nucleus by RNA bound to the protein's dsRNA-binding motifs. The nuclear localization of NF110 is also dependent on RNA binding but is independent of these motifs, and is governed by contacts made to the protein's unique C terminus. During mitosis, about half of the cytoplasmic NF90 becomes dissociated from RNA, but phosphorylation does not impair the binding affinity of either NF90 or NF110 for dsRNA. We conclude that NF90 and NF110 engage RNA differentially and translocate from the nucleus to the cytoplasm in mitosis because phosphorylation disturbs their interactions with other nuclear proteins.
人类双链RNA（dsRNA）结合蛋白核因子90（NF90）家族的成员在有丝分裂开始时会发生磷酸化并转移到细胞质中。我们研究了NF90及其更大的剪接变体NF110的转移机制。在间期，NF90主要位于细胞核中，NF110仅存在于细胞核中，且两者均与RNA结合。大约一半的NF90通过与该蛋白dsRNA结合基序结合的RNA锚定在细胞核中。NF110的核定位也依赖于RNA结合，但不依赖于这些基序，而是由与该蛋白独特的C末端的接触所决定。在有丝分裂期间，大约一半的细胞质NF90会与RNA解离，但磷酸化不会损害NF90或NF110对dsRNA的结合亲和力。我们得出结论，NF90和NF110与RNA的相互作用方式不同，并且在有丝分裂过程中从细胞核转移到细胞质，因为磷酸化会干扰它们与其他核蛋白的相互作用。
