Structured non-coding RNAs and the RNP Renaissance.

Non-protein-coding (nc) RNAs are diverse in their modes of synthesis, processing, assembly, and function. The inventory of transcripts known or suspected to serve their biological roles as RNA has increased dramatically in recent years. Although studies of ncRNA function are only beginning to match the pace of ncRNA discovery, some principles are emerging. Here we focus on a framework for understanding functions of ncRNAs that have evolved in a protein-rich cellular environment, as distinct from ncRNAs that arose originally in the ancestral RNA World. The folding and function of ncRNAs in the context of ribonucleoprotein (RNP) complexes provide myriad opportunities for ncRNA gain of function, leading to a modern-day RNP Renaissance.