Zhang M, Zamore P D, Carmo-Fonseca M, Lamond A I, Green M R
Program in Molecular Medicine, University of Massachusetts Medical Center, Worcester 01605.
Proc Natl Acad Sci U S A. 1992 Sep 15;89(18):8769-73. doi: 10.1073/pnas.89.18.8769.
U2 small nuclear ribonucleoprotein auxiliary factor (U2AF), an essential mammalian splicing factor, is composed of two subunits: a 65-kDa protein (U2AF65), which binds the pre-mRNA polypyrimidine tract and is required for in vitro splicing, and an associated 35-kDa protein (U2AF35). Here we report the isolation of a cDNA encoding U2AF35. U2AF35 contains sequence motifs found in several mammalian pre-mRNA splicing factors. We show directly that U2AF65 and U2AF35 interact with each other and delineate the regions of both proteins that mediate this interaction. Using anti-peptide antibodies against U2AF35, we show that the protein has the intracellular distribution characteristic of U2AF65. Both U2AF65 and U2AF35 are concentrated in a small number of nuclear foci corresponding to coiled bodies, subnuclear organelles first identified by light microscopy in 1903.
U2小核核糖核蛋白辅助因子（U2AF）是一种必需的哺乳动物剪接因子，由两个亚基组成：一个65 kDa的蛋白质（U2AF65），它结合前体mRNA的多嘧啶序列，是体外剪接所必需的；以及一个相关的35 kDa蛋白质（U2AF35）。在此，我们报告了编码U2AF35的cDNA的分离。U2AF35含有在几种哺乳动物前体mRNA剪接因子中发现的序列基序。我们直接表明U2AF65和U2AF35相互作用，并描绘了介导这种相互作用的两种蛋白质的区域。使用针对U2AF35的抗肽抗体，我们表明该蛋白质具有U2AF65的细胞内分布特征。U2AF65和U2AF35都集中在少数与卷曲小体相对应的核灶中，卷曲小体是1903年通过光学显微镜首次鉴定的亚核细胞器。
