Freire M A, Pagès M
Departament de Genética Molecular, Centre d'Investigació i Desenvolupament, C.S.I.C., Barcelona, Spain.
Plant Mol Biol. 1995 Nov;29(4):797-807. doi: 10.1007/BF00041169.
The maize RNA-binding protein MA16 is a non-ribosomal nucleolar protein widely distributed in different maize tissues. We have previously shown that the MA16 protein binds preferentially to guanosine- and uridine-rich sequences. As a step towards the identification of specific targets with which MA16 interacts within the cell, we investigated the RNA-binding affinities and several other aspects of the protein by using binding assays and immunochemistry. The MA16 protein showed a wide spectrum of RNA-binding activities with lower affinities to several RNAs that was salt and heparin-sensitive indicative of electrostatic interactions, and higher affinities to particular RNAs including rRNA and translatable mRNA sequences. Among the RNAs found associated with MA16 protein was that encoding MA16 itself. This observation raises the possibility that MA16 gene expression could be self-regulated. Immunoprecipitation studies showed that in vivo MA16 was phosphorylated and that MA16 interacts with RNAs through complex association with several proteins. These results suggest that both phosphorylation and interaction with other proteins may be involved in determining RNA-binding specificities of MA16 in the cell.
玉米RNA结合蛋白MA16是一种非核糖体核仁蛋白，广泛分布于玉米的不同组织中。我们之前已经表明，MA16蛋白优先结合富含鸟苷和尿苷的序列。作为鉴定MA16在细胞内相互作用的特定靶点的一个步骤，我们通过结合测定和免疫化学研究了该蛋白的RNA结合亲和力及其他几个方面。MA16蛋白表现出广泛的RNA结合活性，对几种RNA的亲和力较低，这种亲和力对盐和肝素敏感，表明存在静电相互作用，而对包括rRNA和可翻译的mRNA序列在内的特定RNA具有较高的亲和力。在与MA16蛋白相关的RNA中，有一种是编码MA16自身的RNA。这一观察结果增加了MA16基因表达可能自我调节的可能性。免疫沉淀研究表明，在体内MA16被磷酸化，并且MA16通过与几种蛋白质的复杂结合与RNA相互作用。这些结果表明，磷酸化以及与其他蛋白质的相互作用可能都参与了确定MA16在细胞中的RNA结合特异性。
