The cis-acting RNA trafficking signal from myelin basic protein mRNA and its cognate trans-acting ligand hnRNP A2 enhance cap-dependent translation

The 21 nucleotide RNA trafficking signal (RTS), originally identified in my elin basic protein mRNA, but also found in a variety of other localized RNA s, is necessary and sufficient for transport of RNA along microtubules in o ligodendrocytes. The RTS binds specifically to the RNA binding protein, hnR NP A2. Together, the RTS and hnRNP A2 comprise cis/trans determinants for s everal steps in the RNA trafficking pathway. Here we show that insertion of the RTS into green fluorescent protein (GFP) RNA enhances translation with out affecting stability of microinjected RNA. In dicistronic RNA, the RTS e nhances cap-dependent translation without affecting internal ribosome entry site (IRES)-dependent translation. The translation enhancer function of th e RTS is position, copy number, and cell type independent, hnRNP A2 depende nt, and saturable with increasing amounts of injected RNA. This represents one of the first specific translation enhancer elements identified in a mam malian system.