Exportin 5 is a RanGTP-dependent dsRNA-binding protein that mediates nuclear export of pre-miRNAs

MicroRNAs (miRNAs) are widespread among eukaryotes, and studies in several systems have revealed that miRNAs can regulate expression of specific genes. Primary miRNA transcripts are initially processed to approximately 70-nucleotide (nt) stem-loop structures (pre-miRNAs), exported to the cytoplasm, further processed to yield approximately 22-nt dsRNAs, and finally incorporated into ribonucleoprotein particles, which are thought to be the active species. Here we study nuclear export of pre-miRNAs and show that the process is saturable and thus carrier-mediated. Export is sensitive to depletion of nuclear RanGTP and, according to this criterion, mediated by a RanGTP-dependent exportin. An unbiased affinity…

• DF
  Deutsche Forschungsgemeinschaft