These sequences may be bound by hnRNPs, marking them for nuclear retention and destruction.  
Initially discovered by electron microscopy of adenovirus sequences and in the mouse beta-globin gene, they may have contributed to speeding the evolution of eukaryotic proteins by increasing the probability of favorable recombination events.  These sequences may be bound by hnRNPs, marking them for nuclear retention and destruction.  Reactions involving them may be self-sustained through ribozymes, or may be mediated by a collection of small ribo-nucleo-proteins in spliceosomes. Their discovery won Sharp and Roberts the Nobel Prize in Physiology or Medicine in 1993.  FTP, name these sequences of RNA which are transcribed but are excised during maturation of mRNA, the counterpart to exons.
Initially discovered by electron microscopy of adenovirus sequences and in the mouse beta-globin gene, they may have contributed to speeding the evolution of eukaryotic proteins by increasing the probability of favorable recombination events.  
introns