Beyond DNA: zinc finger domains as RNA-binding modules.

Over the last 25 years, we have learned that many structural classes of zinc-binding domains (zinc fingers, ZFs) exist and it has become clear that the molecular functions of these domains are by no means limited to the sequence-specific recognition of double-stranded DNA. For example, ZFs can act as protein recognition or RNA-binding modules, and some domains can exhibit more than one function. In this chapter we describe the progress that has been made in understanding the role of ZF domains as RNA-recognition modules, and we speculate about both the prevalence of such functions and the prospects for creating designer ZFs that target RNA.