Rehbein Monika, Wege Konstanze, Buck Friedrich, Schweizer Michaela, Richter Dietmar, Kindler Stefan
Institute for Cell Biochemistry and Clinical Neurobiology, Centre for Molecular Neurobiology, University Hospital Eppendorf, University of Hamburg, Germany.
J Neurochem. 2002 Sep;82(5):1039-46. doi: 10.1046/j.1471-4159.2002.01058.x.
In neurones, the somatodendritic microtubule-associated protein 2 regulates the stability of the dendritic cytoskeleton. Its extrasomatic localization appears to be a multicausal mechanism that involves dendritic mRNA trafficking, a process that depends on a dendritic targeting element in the 3' untranslated region. Two rat MAP2-RNA trans-acting proteins, MARTA1 and MARTA2, exhibit specific high-affinity binding to the dendritic targeting element. We have now affinity-purified MARTA1 from rat brain. Analysis of proteolytic peptides revealed that rat MARTA1 is the orthologue of the human RNA-binding protein KSRP. Rat MARTA1 is a 74-kDa protein that contains four putative RNA-binding domains and is 98% identical to human KSRP. Both purified rat MARTA1 and human KSRP preferentially bind to the dendritic targeting element, but do not strongly interact with other investigated regions of mRNAs encoding microtubule-associated protein 2 and alpha-tubulin. In rat brain neurones and cultured neurones derived from superior cervical ganglia, MARTA1 is primarily intranuclear, but is also present in the somatodendritic cytoplasm. Thus, MARTA1 may play a role in nucleocytoplasmic mRNA targeting.
在神经元中，体细胞树突微管相关蛋白2调节树突细胞骨架的稳定性。其胞体外定位似乎是一种多因素机制，涉及树突mRNA运输，这一过程依赖于3'非翻译区中的树突靶向元件。两种大鼠MAP2-RNA反式作用蛋白，即MARTA1和MARTA2，对树突靶向元件表现出特异性高亲和力结合。我们现在已从大鼠脑中亲和纯化出MARTA1。对蛋白水解肽段的分析表明，大鼠MARTA1是人类RNA结合蛋白KSRP的直系同源物。大鼠MARTA1是一种74 kDa的蛋白质，包含四个假定的RNA结合结构域，与人类KSRP的同源性为98%。纯化的大鼠MARTA1和人类KSRP都优先结合树突靶向元件，但与编码微管相关蛋白2和α-微管蛋白的mRNA的其他研究区域没有强烈相互作用。在大鼠脑神经元和源自颈上神经节的培养神经元中，MARTA1主要位于细胞核内，但也存在于体细胞树突细胞质中。因此，MARTA1可能在核质mRNA靶向中发挥作用。
