Presence of a poly(A) binding protein and two proteins with cell cycle-dependent phosphorylation in Crithidia fasciculata mRNA cycling sequence binding protein II.
Presence of a poly(A) binding protein and two proteins with cell cycle-dependent phosphorylation in Crithidia fasciculata mRNA cycling sequence binding protein II.
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Crithidia fasciculata mRNA 循环序列结合蛋白 II 中存在聚腺苷酸结合蛋白和两种具有细胞周期依赖性磷酸化的蛋白。
DOI：
10.1128/ec.3.5.1185-1197.2004
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Ray,DanS
中科院分区：
文献类型：
--
作者：
Mittra,Bidyottam;Ray,DanS
已经证明，棘豆束状环化序列结合蛋白（CSBP）与存在于细胞周期中周期性积累的几种mrna中的序列元件具有高特异性结合。第一种CSBP的亚基分别为35.6 kDa （CSBPA）和42 kDa （CSBPB）。从mcsbpanull突变细胞中纯化出第二种不同的结合蛋白，称为CSBP II，缺乏CSBPA和CSBPB蛋白，含有三种主要的多肽，预测分子质量为63,44.5和33kda。相同大小的多肽在紫外交联试验中进行放射性标记，使用纯化的CSBP II和32p标记的RNA探针，其中包含六个循环序列拷贝。在细胞周期的进展过程中，发现CSBP II结合活性与靶mRNA水平平行循环。我们克隆了编码这三种CSBP II蛋白的基因，命名为RBP63、RBP45和RBP33，并鉴定了它们的结合特性。RBP63蛋白是聚(a)结合蛋白家族的一员。RBP45和RBP33蛋白的同源物仅存在于着丝质体中。RBP45和RBP33蛋白及其同源物都有一个保守的羧基末端一半，包含一个psp1样结构域。这三种CSBP II蛋白在体外均表现出结合野生型循环序列的特异性。RBP45和RBP33是磷酸化蛋白，RBP45在体内特异性结合含有循环序列的靶mRNA。发现RBP45和RBP33的磷酸化水平在细胞周期中循环。
Crithidia fasciculatacycling sequence binding proteins (CSBP) have been shown to bind with high specificity to sequence elements present in several mRNAs that accumulate periodically during the cell cycle. The first described CSBP has subunits of 35.6 (CSBPA) and 42 kDa (CSBPB). A second distinct binding protein termed CSBP II has been purified fromCSBPAnull mutant cells, lacking both CSBPA and CSBPB proteins, and contains three major polypeptides with predicted molecular masses of 63, 44.5, and 33 kDa. Polypeptides of identical size were radiolabeled in UV cross-linking assays performed with purified CSBP II and32P-labeled RNA probes containing six copies of the cycling sequence. The CSBP II binding activity was found to cycle in parallel with target mRNA levels during progression through the cell cycle. We have cloned genes encoding these three CSBP II proteins, termed RBP63, RBP45, and RBP33, and characterized their binding properties. The RBP63 protein is a member of the poly(A) binding protein family. Homologs of RBP45 and RBP33 proteins were found only among the kinetoplastids. Both RBP45 and RBP33 proteins and their homologs have a conserved carboxy-terminal half that contains a PSP1-like domain. All three CSBP II proteins show specificity for binding the wild-type cycling sequence in vitro. RBP45 and RBP33 are phosphoproteins, and RBP45 has been found to bind in vivo specifically to target mRNA containing cycling sequences. The levels of phosphorylation of both RBP45 and RBP33 were found to cycle during the cell cycle.