Preiser P, Vasisht V, Birk A, Levinger L
School of Life and Health Sciences, University of Delaware, Newark 19716.
J Biol Chem. 1993 Jun 5;268(16):11553-7.
A approximately 50-kDa protein binds specifically to the 3' terminus of 135-nucleotide Drosophila pre-5 S RNA. Unlabeled poly(U) competes out protein binding and stimulates the activity of a 3'-exonuclease, which eventually degrades the substrate to 120 nucleotides, the size of mature 5 S RNA. In its RNA binding and UV cross-linking properties, the endogenous poly(U)-binding protein resembles human La, an autoantigen that binds the U > 3 3' ends of vertebrate RNA polymerase III primary transcripts. This protein appears to inhibit a 3' exonuclease and could protect 5 S RNA for faithful processing and transport.
一种约50 kDa的蛋白质特异性结合135个核苷酸的果蝇前体5 S RNA的3'末端。未标记的聚尿苷酸（poly(U)）能竞争蛋白结合并刺激3'-外切核酸酶的活性，该酶最终将底物降解为120个核苷酸，即成熟5 S RNA的大小。就其RNA结合和紫外线交联特性而言，内源性聚尿苷酸结合蛋白类似于人La，一种与脊椎动物RNA聚合酶III初级转录本的U>3 3'末端结合的自身抗原。这种蛋白质似乎抑制3'外切核酸酶，并能保护5 S RNA进行准确的加工和转运。
